By using experimental ecological methods, the 24 hours semi-lethal temperature (24 h LT50) of typical copepods living in the coastal area of East China Sea was determined to elucidate the effects of thermal discharge from power station on the coastal ecosystem. The results indicated that different copepods at same natural acclimated temperature and specific copepod at different initial acclimated temperature had different thermal tolerance capability. The 24h LT50 of Calanus sinicus and Sinocalanus tenellus at natural acclimated temperature 13.5 degrees C was 26.9 degrees C and 25.4 degrees C, of Acartiella sinensis and Corycaeus affinis at natural acclimated temperature 14.2 degrees C was 26.7 degrees C and 30.5 degrees C, and of Centropages dorsispinatus, Paracalanus crassirostris, Acartia spinicauda and Euterpina acutifrons at natural acclimated temperature 28.0 degrees C was 34.0 degrees C, 34.3 degrees C, 35.7 degrees C and 36.0 degrees C, respectively. The 24h LT50 of S. tenellus at natural acclimated temperature 13.5 degrees C and 23.5 degrees C was 25.4 degrees C and 33.0 degrees C, respectively.