随着经济发展和金融市场的日益开放，商业银行在数量增加的同时竞争也变的日趋激烈，如何高效的控制信贷风险和扩大业务范围成为商业银行面临的首要问题。2011年温州爆发的“借贷危机”又一次把中小企业融资难的问题推上了风口浪尖。国家也更加重视商业银行对中小企业“惜贷”的问题。商业银行之所以“惜贷”是因为中小企业的信贷风险高，银行不能及时对这种风险作出预测，所以必须从商业银行内部尽快建立起科学的信贷风险评估模型对中小企业的信贷风险进行预测。只有这样商业银行才能降低信贷风险，对中小企业的融资进行大力支持从而使双方达到共赢。 本文首先分析了国内外学者的研究成果，总结了目前的信贷风险评估方法和信贷风险相关理论，并选取了适合中小企业的信贷风险评估方法。其次分析了我国商业银行中小企业信贷风险评估现状，指出中小企业的贷款需求得不到满足，商业银行存在信贷风险，商业银行中小企业的信贷风险评估还存在一定的问题。然后根据从某股份制商业银行获取的2011和2012年的90家中小企业的信用正常和违约样本的数据，构建了商业银行中小企业信贷风险评估指标体系，把样本分为建模和检验样本组，先对建模样本组的财务指标进行参数及非参数检验，剔除两组样本不存在显著性差异的财务指标，又通过主成分分析法对建模样本组的剩余财务指标进行筛选，保留了5个主成分，对非财务指标通过专家打分法给予了量化。接着根据保留的财务指标和非财务指标运用Logit回归法构建了中小企业信贷风险评估模型，回归分析后对模型进行了统计检验，对模型的系数进行了解释，然后又将模型对检验样本组的30家样本企业进行检验，得出评估模型对有贷款业务的中小企业发生违约情况的预测概率高达90%。最后，对于如何加强商业银行中小企业信贷风险评估提出了相关建议。

With the development of economic and the financial market open increasingly, the number of the commercial banks has increased,at the same time ,the competition of the commercial banks has became more and more fiercer.The commercial banks’ primary issue is how to efficiently control the credit risk and to expand business scope.In the 2011, The “Private lending crisis” had happened in the city of Wenzhou and which had pushed the financing difficult problem of the small and the medium-sized enterprise to the forefront again.Countries also pay more attention to the problem that why the commercial banks can not lend enough money to the small and medium-sized enterprises.Because of the credit risk of the small and medium-sized enterprise's is higher than the large-scale enterprises,the commercial banks are not to make an accurate prediction about the credit risk in time,so they should establish a scientific credit risk assessment mode from the internal as soon as possible to predict the small and medium-sized enterprise's credit risk.Only in this way, the commercial banks not only to reduce the credit risk, but also to support the small and medium-sized enterprise’s financing problem. Both of the two sides can achieve in a win-win.. 　　　This article first analyzes the research results of scholars both at home and abroad, summarizes the current credit risk assessment methods and the credit risk management related theories, selected the suitable credit risk assessment method for small and medium-sized enterprise .Then the paper has analyzed the credit risk assessment current situation about the commercial banks to the small and medium-sized enterprise and point out that the loan needs of the small and medium-sized enterprise are not being met, commercial banks have some credit risk and the credit risk assessment of the commercial banks to the small and medium-sized enterprises still exist certain problems. Then according to the data of 2011 and 2012 about the 90 　　　mses credit default and normal samples from a joint-stock commercial bank, build the credit risk assessment evaluation index system to the commercial banks small and medium-sized enterprise ,and divided the samples into two groups:the modeling samples and the testing samples,firstly make the independent samples T test to the financial indicators of all the samples and weed out the financial indicators which have no significant difference.Then through the principal component analysis (pca) to screen the rest of the financial indicators of the model samples and retained five principal components.Meanwhile, quantify the non-financial indicators by the expert scoring method. This paper establishes the small and medium-sized enterprise credit risk assessment model according to the logit regression method by the retain financial and non-financial indicators. This paper makes a statistical test after the regression analysis and explain the coefficient of the model.Then,this paper makes a test for the 30 enterprises of the testing samples and draw that the predict probability of default of the model is as high as 90%. Finally, this paper puts forward some related suggestions in order to strengthen the credit risk evaluation of the commercial banks to small and medium-sized enterprises.