In order to study the impact of the thermal environment on the optical performance of the Ha and White light telescope(HWT), a thermo-optical experimental system is built test the optical performance of the HWT under a thermal vacuum condition. This system is made up of four sub-systems: an optical system to be tested, a vacuum system, a temperature measurement and control system, and a wavefront sensing system. The temperature conditions of the thermo-optical testing are designed on the basis of the measurement and numerical simulation of the ground observing condition. An integrated STOP test based on the HWT is performed. The optical performances of the HWT under different vacuum degree and different thermal control conditions are tested using the wavefront sensing system. The results show that when the temperature of the secondary mirror is below 40°C, the optical performance of HWT is about λ/8, which satisfies the requirement of λ/6. The secondary mirror structure is the most effect to the system optical performance, which is the key part improving HWT. After the analytical model of HWT is set up by using the finite element analysis software MSC.PATRAN/NASTRAN, finite element based optical analysis (FEMOPT) software is used to calculate the optical performance. The comparison of the temperature control condition simulation and experimental results show that FEMOPT optical structural thermal integral analysis is reasonable.