中文摘要：

亚洲开发银行在贵州省铜仁地区开展了试点的小额信贷项目，针对没有可供抵押担保财产的借款农户，尝试回答农户为什么接受不同的借款利率；为何基本上与农行等正规金融机构没有借贷关系？基于信息分布设定的Bardhan和uary简化模型，分析表明：无担保小额贷款合约实际上体现了委托代理关系；不同信息条件的借款方保留收益借贷均衡及利率起决定作用。农户间互借口头合约确立时已认可借款方存在“收成”及还款的不确定性；有储蓄余额农户的低保留收益导致利率近似为零；在借款需求无法被亲友间低利率储蓄转移满足的情况下，将出现亲友间借贷与农信社小额信贷两种信用关系并存，后者因不对称信息和高保留收益导致较高的均衡利率；各商业银行的巨大保留导致无法与农户达成无抵押担保借款合约。

英文摘要：

The ADB has developed Microfinance projects to who is not able to afford of the mortgages in Tongren in Guizhou province in order to explain any phenomenon： firstly, why farmers accept different interest rate at one time; secondly, there is no lending from the Formal Financial Institutions. Based on the research of Bardhan and Udry, our analysis indicates that the lending contract without mortgages shows the principal-agent relationship; the equilibrium interest rate depend on the borrower＇s reservation utility in any information structure. The oral contracts between acquaintances show that both side has recognized the uncertainty of borrower＇s return and product; the lender＇s low reservation utility result in the ＂0＂ interest rate; when the needs exceed the supply of ＂0＂ interest rate lending, the ＂0＂ interest rate lending and lending with high interest rate exist at the same time, the high equilibrium interest rate depend on asymmetric information and the borrower＇s high reservation utility; the commercial bank＇s reservation utility is too high to make deal with the farmers.