Abstract: We monitored the seasonal snowline elevation on Tianshan Mountains and analyzed its changing characteristics and impact factors by adopting the snow cover duration ratio method, based on MOD10A1/MYD10A1, MOD13Q1 and related meteorological data from 2001 to 2015. The results show that: ① The overall snowline on Tianshan Mountains have been on the rise significantly in the recent 15 years, with average elevation of about 3 680 meters, wherein the stability of the snow lines on the northern slope of Tianshan Mountains, Yili River Valley and the southern slope of Tianshan Mountains has weakened successively, the average elevations of which are 3 620, 3 390 and 3 820 meters respectively; the snowline elevation in space shows the latitudinal zonality distribution characteristics of being high in the south and low in the north and high in the east and low in the west. ② On the interannual scale, temperature is the main controlling factor which influences the snowline elevation of Tianshan Mountains, with significant positive correlation, so are the case on the south and north slopes of the Tianshan Mountains, while in Yili River Valley, precipitation is the main controlling factor that influences its change, with significant negative correlation; on the seasonal scale, the temperature in summer and the precipitation in winter are the main controlling factors which influence the snowline elevation, precipitation assumes negative correlation with it, while in areas with higher temperature, the precipitation in summer and autumn can facilitate snow melting, which makes the snowline elevation rise; on the monthly scale, the temperature in July and the precipitation in January are most obvious in affecting it, and there exists a certain lag in response. ③ The snowline elevation of Tianshan Mountains is about 800 meters lower than the zero degree layer, the two have a good positive correlation; snowline elevation shows negative correlation with NDVI, in areas with good vegetation cover, NDVI and snowline elevation in the same year have a good correlation, while in areas with poor vegetation cover, NDVI in the previous year has a good correlation with it.