Over the past two decades, the task-based approach is so popular in L2 teaching that more and more attention has been focused on L2 learners’ performance of tasks. In task-based language teaching and SLA research, tasks hold a central place. And it is generally acknowledged that the manipulation of a task can be divided into three main phases, that is, pre-task phase, during-task phase and post-task phase. Pre-task phase is an important stage that influences students’task performance because according to Skehan’s Limited Attentional Capacity Model, human’s attentional resources and information processing capacity are limited. Therefore, how to make good use of this pre-task phase is of great significance to second language learners’writing task, which is acknowledged as a complex process. Based on the writing models of Kellogg and Flower & Hayes, the present study aims at firstly to examine whether pre-task strategic planning affects L2 learners’ writing performance positively and secondly to explore effective pre-task strategic planning conditions that may facilitate L2 learners’ writing performance.The study mainly employed quantitative method and a questionnaire survey is added as a supplement. There are mainly four stages involved in the whole experiment, namely, a pilot study, a homogeneity test, the main experiment and finally a questionnaire survey. In the first place, a pilot study is carried out to guarantee the feasibility of the experiment from the aspect of research materials and research design, and then the selected participants are required to take part in the homogeneity test to make sure that they are at the same level in writing proficiency in terms of fluency, accuracy and lexical complexity. Then comes the main experiment. Finally, a questionnaire survey is implemented as a supplement to the quantitative study. There are totally 147 participants chosen for the main experiment, and they are randomly divided into four groups, including three experimental groups and a control group with the average number of 36. During the process of the main experiment, the three experimental groups are required to finish three different planning worksheets (vocabulary planning, idea-generation and organization) respectively with the time limit being 10 minutes before the writing task, while the participants of the control group are asked to start writing immediately after they get the writing paper without any planning. Finally, their writings are analyzed in terms of fluency, accuracy and lexical complexity. Fluency is measured by T-unit length (W/T), accuracy is measured by Error-free clause ratio (EFC/C) and lexical complexity is measured by Type-token ratio (WTI-(?)). And then all the collected data are analyzed under the help of SPSS 11.5, meanwhile, independent sample T-test is utilized to test the hypotheses. Finally, in order to have a better understanding of the participants minds during their writing process, their questionnaires are analyzed.The results show that pre-task strategic planning will enhance L2 learners’ writing generally. The first type of pre-task strategic planning-vocabulary planning has obvious influence on learners’ writing accuracy and lexical complexity. The idea-generation group produced more fluent writing than the control group. The organization group produced more fluent and accurate language than the control group. So the positive effect of pre-task planning is confirmed. Then the differential effect of different types of planning is examined. The results show that vocabulary planning do have an obvious effect on the participants’ writing in terms of lexical complexity. Concerning the effect of organization, when it is compared with the vocabulary group, there is a statistically significant difference as far as fluency is concerned. However, there is no statistically significant difference between the idea-generation group and organization group in terms of fluency. This may due to that when the participants retrieving the ideas from their long-term memory, they are likely to have an internal presentation of the structure for later writing. So these two types of strategic planning conditions can be said to have similar influence on students’writing fluency. |