Abstract: According to the survey data of the investigation of offshore resources in the northern South China Sea during 2014−2015, we analyzed the relationship among the fishing ground, vertical structure of temperature and water temperature in that area. The results show that the location of fishing ground was closely related to water temperature gradient, and the correlation coefficient of location of fishing ground and temperature gradient was different in different seasons. The correlation between location of fishing ground and temperature gradients of 20−25 m water layer was the highest in spring survey. There was high correlation between location of fishing ground and at the surface layer and 50 m water layer in summer survey. The location of fishing ground was closely related to the water layer of 10−15 m in autumn survey, and the correlation between fishing location and temperature gradient at 15−20 m water layer was the highest in winter survey. It is also found that the fishing ground of the northern South China Sea was sensitive to the change of water temperature gradient. The fishing ground was mainly located in the Beibu Gulf in spring and summer, and mainly in the sea area near the east of Hainan Island in Leizhou Peninsula during autumn and winter.