Abstract: Participating in water user association （WUA） is a kind of rational choice for farmers adapting themself to the changing environment. Using 307 survey data， this paper empirically analyzed the effect of WUA on the rice yield. The results showed that the yield of late rice was significantly improved by WUA， while the yield of early rice was not significantly improved. The results also indicated that agricultural material input， land quality， land location， the number of non\|agricultural employment， farmers age and farming duration had significant influence on the rice yield.

Key words: water user association, rice； yield, instrumental variables