Abstract: Rice-duck cultivation is the essence of Chinese traditional agriculture. A scientific assessment of the mechanism and its capacity is of theoretical significance and practical value in improving modern agricultural technology. The duck's secretions, excreta and their treading, pecking and predation decrease the occurrence of plant diseases, pests and weeds, enrich the species diversity and improve the field environment. Rice-duck intergrowth system effectively prevents rice planthoppers and rice leafhoppers, the control effects can be up to 98.