Purpose /SignificanceOn the basis of the field research data of the philosophy and social science projectof Yunnan Province:Research on Targeted Poverty Alleviation of Farmers′ Co-op in the New Era, this paper tests the marginal effect of the income of farmers who have joined co-ops.

Method /ProcessThe paper takes the education level and the household category of the investigated farmers as the instrumental variables to examine the estimation error caused by the possible endogeneity of joining co-ops.

Result/ConclusionThe study finds out that the income of co-ops farmers has been significantly increased, and it is still significant after adding various control variables and other factors. Apart from that, the paper findsby quantile regression study that the impact of joining co-ops on different income farmers has a linear decline, that is to say, the impact on low-income farmers is the largest, while the impact on middle and high-income farmers is smaller and smaller. Low-income farmers get much more benefit than others.