In this paper, the free-running characteristics of the 633 nm internal-mirror He-Ne laser tube at the ambient temperature of -20-40 ℃ are studied. The experimental results show that when the laser tube reaches the thermal equilibrium at different ambient temperatures, the difference between the laser tube temperature and the ambient temperature is fixed, the expansion rate is also the same, and the voltage difference of the double longitudinal mode changes for the same period. According to these characteristics, the preheating and frequency stabilization control scheme of the laser system is designed, and the frequency stabilization of the 633 nm internal-mirror He-Ne laser is realized. When the room temperature is about 24 ℃, the beat frequency results of the locked thermally stabilized laser and the high-precision iodine stabilized laser show that the relative standard uncertainty of frequency within 3 h is u=6.4×10^-9. When the sampling time τ=1 s, the corresponding Allen variance is 7.0×10^-11. When 0.1 s≤τ≤2000 s, the Allan variance is better than 4.3×10^-10, and the frequency reproducibility within 3 months is better than 4.6×10^-9. This paper also studies the frequency drift law of the output laser after locking at the ambient temperature of -20-40 ℃. The experimental results show that the temperature of the laser tube wall changes linearly with the ambient temperature after frequency stabilization. At the same time, the drift of the laser output frequency with the ambient temperature after frequency stabilization is about 293 kHz/℃, which is consistent with the drift value of 268 kHz/℃ calculated by the pressure estimation model. In this regard, when the laser is working in a large temperature range (such as -20-40 ℃), interpolation calibration can be used to obtain a more accurate reference output frequency.