The extent of seasonally frozen soil is shrinking under global warming. The influence of seasonally frozen soil on spring runoff, especially on the spring peak flow is making the concerned study necessary. In order to analyze the influence and controlling factors of seasonally frozen soil in the mountain areas with different elevation, this study used the path analysis method to analyze the influence and controlling factors of the maximum depth of frost penetration and thawing days in the Kaidu River basin. The results indicate that the influencing factors of the maximum depth of frost penetration and thawing days are similar under different elevation, while the controlling factors are different. The controlling factors of the maximum depth of frost penetration change from the negative accumulative temperature and maximum snow depth in lower elevation to average relative moisture in middle and high elevation. The controlling factor of the thawing days change from the average wind speed and maximum frozen depth in lower elevation to average relative moisture in high elevation. The difference is primarily determined by the geophysical condition and local climate condition in different elevations.