By designing a composite heat sink based on diamond micro-groove structure, the utilization of thermal conductivity difference changes the heat flux conduction, to optimize the problem of heat accumulation in the center of the VCSEL surface array due to uneven temperature distribution, thus improve the overall output power and reliability of the laser surface array. Based on the finite element analysis, a three-dimensional thermoelectric coupling model was established to study the effect of vertical-cavity surface-emitting laser surface array unit arrangement on the thermal crosstalk effect of the laser. Moreover, the effect of the change of microgroove shape and position in the diamond composite heat sink on the internal temperature of the semiconductor laser was also studied and analyzed. And the optimal structure was designed for further optimization of the laser output performance. The vertical-cavity surface-emitting laser facet array with diamond composite heat sink reduces the temperature difference of the laser emitting unit by 29% compared with the conventional diamond heat sink package structure. This provides a new idea for output power optimization of large-area semiconductor laser facet arrays.