This paper discussed the food species and its present frequency, intestine fullness, gill rake structure and food species, based on Protosalanx hyalocranius and zooplankton taken from Daoguanhe Reservoir from March 1995 to June 1997. It showed, with Protosalanx hyalocranius grown, that the distance between gill filters and the food size increased. There existed anegative relationship of food species in intestine and in the environment and a positive relationship of the intestine fullness and growth.