【Objective】This project aims to study the spatial and temporal pattern of the net primary productivity ( NPP) in the northern slope of Tianshan Mountain,analyze the relationship between NPP and climate factors and provide scientific basis for rational exploitation,utilization and management of natural resources there.【Method】The CASA model was used to estimate the NPP of vegetation in the northern slope of Tianshan Mountain in 2015 and its spatial and temporal variation characteristics of the year were analyzed. In addition,the correlation between NPP and climate factors was analyzed by using the correlation analysis method. 【Result】( 1) In 2015,The total NPP of the northern slope of Tianshan Mountain was 34.57 TgC /a,with an average of 173.34 gC /( m~2·a) . The NPP in central and western regions accounted for 82.25%,which was the main supply area,and the average value of NPP in the mountainous region was the highest. ( 2) The NPP of different vegetation types was different,in the forestland,cultivated land,grassland and unused land, they were 534.47 gC /( m~2·a) ,333.47 gC /( m~2·a) ,174.20 gC /( m~2·a) and 124.18 gC /( m~2·a) respectively. ( 3) The total fluctuation range of vegetation NPP was between 0.29 - 3.00 TgC /mon in the northern slope of Tianshan Mountain,and in June it reached the maximum of the whole year,which was 7.39 TgC / mon. Grassland NPP had the largest fluctuation amplitude with seasons,while woodland had the smallest one. The seasonal variation of NPP was summer > spring > autumn > winter. ( 4) The influence of temperature on different vegetation types in northern slope of Tianshan Mountain was greater than that of precipitation. 66.06% of NPP changes were driven by climate factors,mainly concentrating in the central and western regions of the northern slope of the Tianshan mountains. The impacts of non climatic factors accounted for 33.94%,mainly concentrating in the east midlands in the northern slope of Tianshan Mountain.【Conclusion】 The NPP of the northern slope of the Tianshan Mountain shows a trend of " west high and east low" ,different vegetation trends vary with the seasons,and the temperature is the main influencing factor of the change of vegetation NPP in the northern slope.