Base on influence of underground temperature and humidity on belt conveyor failure, the least square fitting method was used to analyze a large amount of data from statistics of Houerxinhe Mine. The results showed that failure rate of belt conveyor was lowest with temperature of 15 ~ 23℃; failure rate of belt conveyor was highest with temperature of 11 ~ 15℃, and with the increasing of temperature, the failure rate was reduced; the failure rate of support increased rapidly when  temperature was 23℃, and as the temperature rose, the rate of failures continued to climb. When the humidity index was 50 % ~ 63 %, the failure rate was very low, both of which were less than 0.6 %; When the humidity index was 30 % ~ 50 %, the rate of failure was decreasing with the increasing of humidity; When the humidity index was 63 % ~ 80 %, the rate of failure showed a rising phenomenon with increasing of humidity.