The integrated rice and duck farming system, as a comprehensive environmental-friendly planting-breeding technique, is developed from Chinese traditional farming-raising ducks in paddy fields. There is a mutualism relationship between rice and duck when they grow together in paddy fields. Ducks can take controls on some harmful organisms in the fields. This paper reviewed the effects of rice-duck farming system on rice diseases, pests, weeds and beneficial insects in China. Based on the study, the results showed that the integrated rice-duck farming system can effectively control most weeds, some species of insect pests, and several kinds of diseases of rice. However, it can also have some effects on beneficial insect populations. It also suggested that further studies on the effects and mechanics of raising ducks to control the pests, diseases, weeds and beneficial insects are needed.