| Drought and soil erosion caused by seasonal maldistribution of rainfall influenced ecological environment and agricultural production. Conservation tillage can effectively reduce soil and water loss. To quantify effects of conservation tillage on volume and processes of Runoff-sediment-yield can clear understand the benefit and mechanism of conservation tillage. Simulated rainfall and text box are used to quantify impacts of straw cover amount and stubble height on volume and processes of Runoff-sediment-yield. Probe into the effect and mechanism of conservation tillage reduce soil and water loss .The main results are as follows:1. Straw-cover amount has significant impacts on Runoff-sediment-yield volume. When the amount of straw cover increased form 0 to 5000kg/hm~2, the accumulated runoff volume decreased 47.1%, the accumulated sediment production decreased 88.8% under no crop planting; the accumulated runoff volume decreased 57.9%,the accumulated sediment production decreased 97.5% under maize planting. Accumulated runoff volume showed a positive linear correlation and accumulated sediment production showed a negative exponential correlation with straw cover amount.2. Straw-cover amount has significant effects on Runoff-sediment processes. Runoff volume tended to increase with the process of rainfall. Within 10~15min after runoff production, Runoff volume increased sharply, then the increased slowly and tended to be stable. The runoff yielding time was prolonged and the fluctuation of runoff processes was small with the increase of straw cover amount. The fluctuation of runoff processes in maize planting plot was smaller than in no crop planting plot. The Sediment production change was large In earlier rainfall course, with rainfall time, the variation decreased and tended to stable after runoff production 15～20min. The processes of runoff and sediment yield were described as power function.3. With the same slope, the accumulated volume of runoff and sediment were reduced with the increase of stubble height. When the stubble height increased form 5cm to 25cm, the accumulated runoff volume decreased 13.8%～30.6%, the accumulated sediment production decreased 32.1%～48.1%.And with the same stubble height, the accumulated sediment increased with the increase of slope, when the slope less than 10 degrees, the accumulated runoff increased with the increase of slope, when the slope more than 10 degrees the accumulated runoff decreased with the increase of slope. Accumulated runoff volume showed a positive linear correlation and accumulated sediment production showed a negative exponential correlation with stubble height.4. The runoff yielding time was prolonged with the increase of stubble height and meanwhile advanced with the increase of slope. The slope gradient has greater influence on runoff and sediment yield processes than stubble height. The processes of runoff and sediment yield were described as power function.5. With the same straw cover amount, the accumulated runoff volume of cultivated loess soil decreased 4.2%～15.6% compared with Lou soil, and the accumulated runoff volume of sandy loess soil decreased 33.6%～50.3% compared with Lou soil. But the accumulated sediment production of cultivated loess soil increased 39.5%~87.9% compared with Lou soil, and the accumulated sediment production of sandy loess soil increased 67.1%~94.3% compared with Lou soil. When the amount of straw cover increased form 0 to 5000kg/hm~2, the accumulated runoff and sediment volume of Lou soil decreased 47.1% and 88.8%, and the accumulated runoff volume of cultivated loess soil decreased 50.7% ,and the accumulated runoff volume of sandy loess soil decreased 60.3%, the accumulated sediment volume of cultivated loess soil and sandy loess soil have no obvious reduce.6. Straw Cover on different soil have different impact on processes of runoff and sediment yield. With the same straw cover amount, the runoff yielding time of cultivated loess soil was later than Lou soil, and the runoff yielding time of sandy loess soil was last. Within 15min after runoff production, runoff volume of Lou soil increased sharply, and within 20min after runoff production, runoff volume of cultivated loess soil increased sharply, and within 33~36min after runoff production, runoff volume of sandy loess soil increased sharply, then the increased slowly and tended to be stable. The Sediment production of Lou soil was large in earlier rainfall course, with rainfall time, the sediment decreased and tended to stable. The Sediment production of cultivated loess soil was larger than Lou soil in earlier rainfall course, and then the sediment decreased, but did not tend to stable. The Sediment production of sandy loess soil was largest in earlier rainfall course, then the sediment decreased, but at the end of rainfall, the Sediment production increased sharply. The processes of runoff and sediment yield of Lou soil and cultivated loess soil and sandy loess soil were described as power function.
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