The paper has brought forward a new encapsulation technique of semiconductor laser arrays. By turning the heat sink shape into a step model,the chip front cavity surface heat will be rapidly spilled out under laser static working condition and it will reduce the temperature difference of laser chip front and back cavity surface. So COD threshold value is increased and the cavity surface degenerate rate is depressed. And these will be propitious to fiber coupling encapsulation. Ansys software simulates the temperature distribution of high power laser arrays in static working condition. The result is that the temperature difference of the chip front and back cavity surface,which uses general heat sink encapsulation technique,is 9.0 K,and the other difference in temperature is 3.5 K which uses the new step model heat sink encapsulation,and it reduces 60%. The difference in temperature of the heat sink front and back surface is also reduced from 18.2 K to 8.0 K. Experimental results match the theoretical analysis well.