Abstract: A practical method for screening and evaluating the optimum proportion of pesticide mixtures was proposed based on the bioassay techniques in laboratory. The method was applicable for research of seeking the optimum proportions of binary mixtures of insecticides. As a case studied, the optimum allocation of insecticide mixtures between dimethoate and fenobucarb was achieved successfully with the 4th instar nymph of Nephotettix cincticeps as the tested insect using the method. The results consisted with what anticipated.