The alignment accuracy of the emitting and receiving optical axes of laser communication equipment in the satellite ground field is crucial. Temperature fluctuation can cause deformations of optical components and mechanical structures, affecting the optical axis’ alignment and reducing the system’s detection accuracy. We design a high-precision optical axis stability system for detection. First, according to the technical requirements of broadband and conjugate imaging, an off-axis reflective Keplerian telescope system with image transfer was applied to compress the beam. After passing through a beam splitter, the beams entered the detection subunit separately. A long focal length optical axis stability detection system was designed to improve detection accuracy. To correct the thermal difference of the reflective system, an optical passive non-thermalization technique was employed using a refractive mirror group to compensate for the thermal-induced aberration of the reflective mirror group. The mechanical structure was designed and subjected to finite element analysis. Finite element data were processed and fed into optical software to simulate the optical axis deviation angle caused by temperature fluctuation. Finally, experiments were conducted for validation. The results show that the optical axis stability detection system has an optical axis deviation angle of 3.90" at -10 °C and 4.23" at 45 °C, reducing the impact of temperature fluctuation on optical axis deviation.