The relationship between the output performance and the working temperature of the fiber laser is studied both in theory and experiment. A numerical model based on laser rate equations concerning the change of pump wavelength is built up and used to calculate and analyze the temperature shift influence of some key components on the change of laser performance. By building the experiment configuration with 915nm wavelength pump light input, the output power and spectrum of the fiber laser are measured while changing the temperature of certain devices like laser diode (LD), grating and doped fiber. Compared with the calculation result, the experimental results suit the model simulation. The fiber laser holds working stability with about 140 W output in the set cooling range of temperature from 15 to 40℃. The temperatures of all the key components except the pump stripper are controlled below 55℃. The fiber laser has certain good performance under different temperature conditions.