TianQin is a space-based gravitational wave observatory in a high geocentric orbit, exposed to space radiation heat sources. This study evaluates the thermal properties combined with the physical and mechanical properties of several materials, concluding that ULE® and Zerodur® are superior choices for optical path stability within the 0.1 mHz to 1 Hz frequency range, with Zerodur showing superior performance. Their ultra-low coefficients of thermal expansion (CTE) ensure minimal length variations due to temperature fluctuations. Their high thermal conductivity and heat capacity further enhance their ability to reduce noise effectively.