By using ANSYS finite element software, the internal distribution of heat fields and heat flow vector in an optically pumped semiconductor vertical-external-cavity surface-emitting laser (OPS-VECSEL) was simulated. The heat performance of OPS-VECSEL with two different configurations of heat dissipation was compared. Besides, the effects of parameters of pump spot and thickness of heatspreader on temperature rise of VECSEL were discussed. Simulation and analysis show that the temperature rise of OPS-VECSEL with double diamond heatspreaders is much lower as well as the resonate wavelength difference at larger pump power density, and meanwhile it is beneficial for heat dissipation because the heat transports to the top and bottom side of OPS-VECSEL chip. With pump power density increasing, the superiority of heat dissipation becomes more notable. It is also showed that better heat dissipation will be achieved when the top diamond thickness is 500 μm and the bottom diamond thickness is 300～500 μm.