As a key indicator for measuring terrestrial ecosystems and an important part of the surface carbon cycle, net primary productivity (NPP) can reasonably assess ecosystem changes and sustainability. Based on MOD17A3 data and using GIS spatial analysis, correlation analysis, and geodetector model, this paper discussed the spatio-temporal pattern and dynamic variations of NPP in Qinling-Daba Mountains from 2000 to 2014. At the same time, the quantitative analysis on the natural and human factors affecting NPP were carried out in order to identify the main influence factors. The results showed that:(1) in the past 15 years, the growth rate of total NPP in Qinling-Daba Mountains was 0.65TgC a^-1 with a fluctuating increase trend. The average NPP per unit area was 493.09gC m^-2 a^-1 with obviously regional differences. The NPP was higher in the west and lower in the east part of study area. (2) The total NPP of different vegetation types was different. Broad-leaved forest and cultivated vegetation were the most important types contributing to the ecosystems of Qinling-Daba Mountains. (3) The NPP changes in stages with elevation and slope, among which the extent of slope's influence on NPP was weaker than that of elevation, and NPP had a significant positive correlation with rain, temperature, and evapotranspiration. (4) There were significant differences in the contribution rate of the natural factors to the NPP (P < 0.01) with the order of ET > rain > temperature > elevation > slope. The contribution rate of interaction between any two natural factors was higher than that of single factor, that is, the NPP in the study area was affected by interaction of multiple natural factors. (5) The impact of human factors on the NPP was manifested as the profit and loss of total NPP caused by the change of land use type, which can be divided into the positive effect of returning forest and grassland and the negative effects of urban development and human destruction.