Multiphysics finite element analysis was used to simulate the heat distribution in a optical pumping semiconductor vertical-external-cavity surface-emitting laser (OPS-VECSEL). Specially,the VECSEL with a plate of transparent diamond that capillary bond to on cap layer of chip was calculated. Calculation indicate that when there is no diamond piece,the temperature difference between first and the last quantum well is about 150 K. But when the cooler is present,the temperature difference between them is very small as well as the resonale wavelongth difference. In addition to diamond piece,a silicon microchannel cooler soldered onto DBR side of chip ulteriorly decreases the temperature difference between quantum wells and optimizes character of the chip. Simulating calculation also shows that properly increasing the diameter of pumping optical speckle was obviously able to lower the thermal effect,specially the heat lens effect.