[Aim]  Two bioassay methods were used to evaluate the toxicities of different types of insecticides against Maruca vitrata larvae, and to establish the relative susceptibility baselines of M. vitrata to commonly used insecticides, in order to provide reference for systematically resistance monitoring and management of M. vitrata in China. [Methods]  The susceptibility of the 3rd instar larvae of M. vitrata to eight commonly used insecticides (chlorantraniliprole, cyantraniliprole, indoxacarb, emamectin benzoate, abamectin, spinetoram, lufenuron, broflanilide) belonging to five insecticide categories were determined by diet surface overlay bioassay method and diet incorporation bioassay method, respectively. Based on the bioassay results, the relative susceptible baselines of M. vitrata to these eight insecticides were established. [Results]  The LC₅₀ values of the above eight insecticides to M. vitrata larvae were 0.007-1.413 μg/cm² by diet surface overlay bioassay, and 0.025-4.178 mg/L by diet incorporation bioassay, respectively. Compared with the diet surface overlay bioassay method, the bioassay data obtained in diet incorporation bioassay method had smaller chi-square value and larger P-value. At the same time, M. vitrata populations showed higher genetic purity of the population in the diet incorporation bioassay method than in the diet surface overlay bioassay method, and also showed the highest repeatability of bioassay results. So it is the recommended bioassay method of these commonly used insecticides against M. vitrata larvae (except indocarb). [Conclusion]  The relative susceptibility baselines of M. vitrata larvae to eight commonly used insecticides have been established using two different bioassay methods respectively, providing reference for the resistance monitoring and chemical control of M. vitrata in China.