Abstract: To study the spatial and seasonal variations of food composition of Hypophthalmichthys molitrix and Aristichthys nobilis and the diet overlap with Neosalanx taihuensis, gut contents of 93 Hypophthalmichthys molitrix and 71 Aristichthys nobilis in Lake Erhai were collected from July 2010 to October 2011. The results showed that 75 and 64 genus of preys ingested by H. molitrix and A. nobilis, respectively. Microcystis and Bosmina sp. were the dominant preys of the two fish species based on the index of relative importance (IRI%). The seasonal variations of food composition of the two fishes were significant, which were closely related to the variations of food resources in the area. The proportion of phytoplankton ingested by H. molitrix and A. nobilis in Gusheng was greater than those in northern Erhai, which resulted from the different food compositions in these two regions. The Schoener overlap index revealed no significant dietary overlap between the two fish species and N. taihuensis (E0.6).