Research On Decision Model Of Optimal Pledging Rate Of Ameliorating Goods Based On The Weibull Distribution

China is a country of large population, agriculture not only affects the smooth and healthy development of the domestic economy, but also the key to the food supplying of 1.3 billion people. The spirit of 14 th National Congress of the party guided the agriculture and rural areas of our country to a new developing period, the sixteen session of the Fifth Plenary Session proposed the construction of a new socialist countryside slogan, and the recent central No. 1 document also broadened the space for agricultural development. The development of agricultural industrialization is the inevitable trend of the market economy development, and the industrialization of agriculture requires substantial financial support. However, due to the characteristics of decentralized management, low level of education, lack of funds and weak risk awareness etc. in china, small farmers encountered financing difficulties and bottleneck in the developing process. Although there are various provinces and cities have the rural credit cooperatives, rural financial banks and other institutions, financial institutions still holds cautious attitude towards agricultural loans.On the background of this circumstances, “Baotuan loans” has been received more and more attention.Based on the existing documents on agricultural products, this paper aimed at the difficulty in financing for the middle-sized farmers, based on the mode of joint guarantee of couple middle-sized farmers, took living modified products as the research object, icombined the modified product and bank mortgage business and established the optimal ratio decision model. The specific contents are as follows:First of all, in a hypothetical of lending relationships of couple farmers“Baotuan loans”banks and logistics companies, and banks pursue the maximization profit. During the development process of agricultural modified products, the net improvement rate is above zero, the time of growth obeys Weibull distribution. Considering whether farmers repaid or not in the ending, set up the decision-making model of the optimal ratio of the bank,and the results showed, the optimal ratio increases with the increasing of farmers’ repayment probability and reduces with the increasing of the deposit rate.Then, on the basis of this, from the point of bank risk controling, this paper considered the involving of Guarantee Corporation during the pledging process. The Guarantee Corporation shall bear part of the loss when farmers defaulted in the business, thus obtained the optimal ratio under circumstances that bank pursues the maximum profit. The study showed that the optimal ratio increases with the increasing of Guarantee Corporation bearing rate and reduces with the increasing of the deposit rate.Finally, based on the above research, from the point of controlling risk for the banks, this paper set up the optimal pledging rate model with the method of down-sized risk controlling, and obtained the optimal pledging rate.At the same while, this paper used the empirical analysis with the help of SPSS to obtain the parameter values of Weibull Distribution, and verified the conclusion with statistic analysis.