The micro-channel heat sink is an effective way to solve the heat removal problem in high power semiconductor laser array. The temperature in a high power semiconductor laser is analyzed by the finite element method. The temperature is obtained in a single and 3, 5, 9 micro-channels heat sinks with the space of 100 μm and transverse size 200μm×60μm. The effect of number of micro-channels on maximum temperature is presented. The result shows that the temperature in the semiconductor lasers in 36 A injected current stable operation can be cooled down to 306 K by the heat sink made up of 9 micro-channels, while the temperature is dropped to 342 K for a single micro-channel. The temperature distribution is also simulated with increasing the space between micro-channels. It is found that the temperature can be dropped to 308 K by 5 micro-channels with the space of 260 μm.