Temperature and thermal stress of high-power photonic crystal fiber (PCF) lasers were numerically simulated and analyzed. Equivalent thermal conductivity was introduced to simplify the structure of photonic crystal fiber,and then three dimensional temperature field model of photonic crystal fiber laser was established. By using the finite element method,the distributions of the temperature in fiber and the thermal stress in end-surface of fiber were numerically simulated and analyzed with natural and forced convection heat transfer,respectively. The results show that the selected PCF can support the pumped power of 1000 W under forced convection heat transfer,but improving the parameters of fiber is required to further enhance the output power by supporting higher pump power.