Abstract: A new type of heat sink for solid-state laser, namely pin-fins heat sink, was presented. Three typical structure designs of water cooled pin-fins heat sink, as well as traditional cavity structure and invariable cross-section mini-channel heat sink, were simulated with Computational Fluid Dynamics (CFD) method. The influence of cooling water flow rate on the characteristics of these approaches, such as gain media maximum temperatures, cooling surface temperature profiles, and pressure losses of heat sinks were comparatively investigated. On the assumptions of equal heat transfer rate and equal flow rate, the heat transfer characteristics of pin-fins heat sink mini-channel heat sink were better than cavity structure heat sink remarkably. The heat transfer resistance of pin-fins heat sink is less than that of minichannel heat sink; meanwhile the flow pressure loss of pin-fins heat sink is greater. Numerical simulation results suggest that pin-fins heat sink has a better performance compared with traditional cavity structure and mini-channel heat sinks. The heat transfer performance of pin-fins heat sink is slightly better than that of invariable cross-section mini-channel heat sink at a higher flow rate, and remarkably better while at a lower flow rate.