Four groups of Tilapia nilotica were fed in different ranges of temperature (constant temperature of 28℃ and 30℃; periodic fluctuating temperature of 28±4℃ and 30±4℃)in the laboratory. The increasing body weight and oxygen consuming rate were measured. The energy assimilating rate and tissue growing rate (K₂) were calculated. The results indicated that the growth of fluctuating temperature groups was faster, and the daily increase weight and percentage increase weight were higher than that of the controlled ones. In addition, the energy assimilating rate and tissue growing rate in the fluctuating temperature groups were higher than that of the controlled groups, except that the tissue growing rate in the fluctuating temperature group at 30±4℃ was lowest. The mechanism that fluctuating temperature promoted the growth of Tilapia nilotica and its significance in productive practice were discussed and analysed.