Abstract: Realized heritabilities (h²) of resistance to F-M mixture (fenvalerate+malathion) and its components in Lipaphis erysimi (Kaltenbach) and Helicoverp aarmigera (Htibner) and to CPM mixture (cyhalothrin+parathion-methyl+methomyl)and its components in Helicoverpa armigera were estimated by threshold trait analysis.The values of h² to mixtures in Lipaphis erysirni and Helicoverpa armigera were smaller than that of its components significantly, and the order was: pyrethroid>carbamate>organophosphorus〉mixture. The application lifetime of the two mixtures was longer than the total of its compoments's lifetimes respectively, resistance risk was: pyrethroid >carbamate>organophosphorus>mixture. Both F-M mixture and CPM mixture could delay resistance development, and CPM mixture was better in delaying resistance development in Helicoverpa armigera.