There are often no formal mechanisms,such as social security and commercial insurance,to protect farmers from risks in developing countries.So the farmers usually avoid risks through the risk pooling in social network,transmitting income span periods and conservative production behavior.Our empirical study indicates that the formal institutions of risk avoiding are almost absent in the rural region of China.The effects of the risk pooling in social network and transmitting income span periods are limited because of the absence of forcible implement mechanism and liquidity constraint,so the conservative production behavior play the most important role,but it causes the low efficiency of running agriculture industry.