Abstract: Hermetia illucens larvae are a valuable resource insect that decompose various agricultural organic wastes．EM bacteria agent is a composite microbial bacteria agent commonly used in food additives, breeding disease control, soil improvement, manure fermentation, etc., and can quickly form dominant colonies in environment to promote decomposition of organic matter and control reproduction of pathogenic microorganisms．This experiment set three groups: fresh pig manure treated with Hermetia illucens larvae alone, pig manure treated with EM bacteria agent and Hermetia illucens larvae, and pig manure treated with EM bacteria, to observe growth and harvest of Hermetia illucens larvae, measure nutrient content of larvae and larvae substrate, and to explore feasibility of synergistic treatment of fresh pig manure with Hermetia illucens larvae and EM bacteria．Results showed that the best comprehensive effect was achieved in synergistic treatment of fresh pig manure with Hermetia illucens larvae and EM bacteria agent, it could harvest about 61 g per kilogram of pig manure, and residual larvae substrate was about 292 g, and average weight and length of single larva was about 0.055 9 g and 1.34 cm．There was no significant difference in nutrient content of larvae and larvae substrate among three treatments, and larvae substrate harvested in each group met criteria for organic fertilizer．Judging from above data, Hermetia illucens larvae well decomposed fresh pig manure, while EM bacteria agent promoted growth of Hermetia illucens larvae．Therefore, synergistic treatment of fresh pig manure with Hermetia illucens larvae and EM bacteria agent is more feasible compared with direct treatment with Hermetia illucens larvae．