Abstract: According to the survey data obtained in northern East China Sea and southern Yellow Sea from Dec. 2007 to Jun. 2008, we studied the composition and diversity of catches by stow net. The results show that there are 41 kinds of fish, 22 crustaceans and 3 cephalopods. The catches are mainly composed of 10 species such as Pseudosciaena polyactis, Trichiurus haumela, Apogon lineatus, Todarodes pacificus, Loligo bleekeri and Ovalipes punctatus. Their weightoccupies 79.86% ofthe total catches. After analyzing the composition of length and weight of small yellow croaker and hairtail juveniles, we find they occupy 97.20% and 61.00% of the catches, respectively. The species abundance and diversity index indicate that the value of fish is rather high in January while relatively low in April, May and June. Crustaceans have higher value in May and lower one in April. Juveniles occupy a relatively high proportion of the catches by stow net, which damages thecommercial larval rather seriously.