It is shown by the results of analyzing investigating and field detected data that the impact scope of Zhanjiang thermal power plant to the aquatic ecosystem in Maxiehai canal is mainly limited within the narrow area with 2℃ temperature increases,which is close to the drainage outlet.The impact of water temperature increase caused by the warm water drainage from the plant to plankton and fish behaves as the decreases of kinds and quantity within the high temperature increase area in summer,and litde influence to fishery production and ocean microbes.But the process of water intake to the plant may form punching and ramming harms to big aquatic organisms and fishes.