Abstract: Athetis lepigone has become one of the major insect pests of summer corn at seedling stage. Information about the characteristics of the overwintering generation and the natural enemies of overwintering larvae of A. lepigone is still limited so far. Age structure of overwintering larvae and biological characteristics of the mature overwintering larvae of A. lepigone were investigated. Natural enemies and pathogens that resulted in A. lepigone larval death were identified or isolated. The 4th instars and older larvae of overwintering A. lepigone shelter in cocoon in the winter, most larvae pupate in cocoon, but some climb out for food and then pupate in the spring. Body length, weight and head width of the overwintering larvae varies to a great extent, and no significant correlation was found among these parameters. Pupal size also differ greatly. Female moths are mostly smaller than male. Oviposition lasts 5－11 d. Number of deposited eggs per female is 277 on average. Longevity of male and female moth is 11.00 d and 18.67 d, respectively. Four species of parasitoids were identified, which parasitized 5.22% of the collected larvae. Pathogenic fungi, such as Beauveria bassiana, Metarhizium anisopliae, Aspergillus flavus and Penicillium spp. were isolated, which resulted in 60.29% mortality of A. lepigone larvae. Pathogenic bacteria, such as Serratia marcescens, Coccus spp.and a Bacillus spp. were also isolated, which caused a total mortality of 21.74%.