The dynamic balance among the external thermal environment changes of the spaceborne laser, the influence of internal high heat flux density heat sources, and the effectiveness of thermal control measures creates the complex and variable temperature field of the spaceborne laser. To optimize the structural thermal control design and improve the temperature field environment, thereby further reducing the impact of thermo-optics, this article conducts an integrated optomechanical-thermal analysis of the laser. By establishing a detailed structural thermal control model and structural model of the laser, high-precision temperature field mapping is achieved. Through ray tracing to simulate thermoelastic deformation, the optical performance changes of the laser under the influence of the temperature field are obtained. The analysis indicates that under thermal disturbances, the laser maintains excellent polarization, stable spot morphology, and the thermal stability of the output beam pointing is better than 4 arcseconds, meeting the performance requirements of the laser.