Keystone species play an irreplaceable role in ecosystems and play a decisive role in the stability and succession of community structures. Based on the bottom trawl surveys from March to December in 2011 in Haizhou Bay and adjacent waters and reference historical literature, SURF (Supportive Role to Fishery ecosystems) index was calculated to identify keystone prey species in Haizhou Bay food web. In the matrix, we analyzed the ratio of food intake and predators for each species, and calculated the value of each species' key indicator (SURF_i). The top five prey species were Leptochela gracilis, Acetes sp., Latreutes planirostris, Alpheus japonicus and Engraulis japonicus, which are keystone prey species in the Haizhou Bay ecosystem. As key prey species, they have relatively low trophic levels, which not only affect energy flow and mass transfer, but also control species diversity in the ecosystem. They play key roles in the control of the entire food web, and their fluctuations may have direct or indirect effects on other species in the Haizhou Bay food web. Therefore, it is critical to protect the key prey species for maintaining the health and stability of Haizhou Bay ecosystem.