Thermal discharge from direct cooling power plant has serious influence on environment and ecosystem of water. In order to analyze the degree of this influence

the silver carp

a commonly seen economic fish spiece

was taken as the research object to carry out numerical simulation on temperature distribution of surrounding water of thermal discharge

by using the Fluent software. The simulation considers four different arrangements for warm water discharge

namely the bottom-vertical type

lateral-middle type

lateral-bottom type and downstream-middle type. The heat-affected areas of the silver carp in summer and winter at the incipient lethal temperature

critical thermal maximum temperature and avoided temperature were obtained

and then the influence coefficient EI under four arrangements of thermal discharge were determined through the comprehensive index method. It can be concluded that the thermal discharge from power pants has a great influence on silver carp in summer and the order of arrangement influence is downstream-middle type

lateral-middle type

lateral-bottom type and bottom-vertical type. The results will provide important reference for the choice of arrangements of thermal discharge in power plants.