Abstract: A field experiment was conducted to study effects of different rice-based cropping systems on DPW (diseases, pests and weeds) hazards and yield of rice. The experiment was designed to have four treatments, i.e. conventional rice farming system (CR, control), conventional Oenanthe javanica farming system（CO）, conventional intercropping of rice with Oenanthe javanica (CRO) and organic intercropping of rice with Oenanthe javanica (ORO). Results show that Treatments CRO and ORO were obviously lower than Treatment CR in DPW hazard; for instance, 45.12% and 47.58% lower, respectively, in number of hills infected with rice leaf blast at the early tillering stage, 41.38% and 6.80% lower, respectively, in number of leaves infected with the disease at the late tillering stage, 69.77% and 44.39% lower at the booting stage and 82.80% and 78.08% lower at the maturity stage, respectively, in number of rice planthoppers, and 48.36% and 39.34% lower in weed density, respectively. Treatment CRO and Treatment ORO was 1.11 and 1.33, respectively, in land equivalent ratio (LER) and 11.31% and 33.11% higher than Treatment CR in yield. In a word, the agroecosystem of intercropping rice with Oenanthe javanica especially in organic mode is obvious in comprehensive effect.