This paper is an attempt to get the food chain structure of Japanese Spanish mackerel,Scomberomorus niphonius (Cuvier et Valenciennes), in the Bohai Sea. The major part of samples were obtained from investigation of fishery resource in Bohai Sea from 1982 to 1984. The stomach content of Japanese Spanish mackerel and the important food species were analized grade by grade. The parameters including weight percentage, number percentage and frequency were used to compare the importance among the food items. The important food species.in every trophic level were obtained from stomach-content data. These species constitute the food chain structure of Japanese Spanish mackerel which includes four trophic levels. The changes of food chain structure between Summer (May to Augest)and Autumn (September to November) were discussed. The conclusion was reached that the structure in Autumn is most complicated. The mean trophic level of the important species were evaluated with the method developed by Odum and Heald. Japanese Spanish mackerel whose mean trophic level is 4.2 occupied the highest trophic level of the food chain, and the mean trophic levels of others are:carnivore 3.1-3.3, plankton,2.0-2. 9, phytoplanton 1.0.