Abstract: The gross primary production (GPP) of vegetation acts as a key indicator for assessing the carbon sink potential of ecosystems. Accurate GPP estimation holds great significance for achieving the goals of peak carbon dioxide emissions and carbon neutrality. Using the difference analysis, one-way analysis of variance (ANOVA), and three-cornered hat (TCH) methods, this study investigated the spatiotemporal differences and uncertainties of three representative remote-sensing-based GPP products: the Moderate Resolution Imaging Spectroradiometer (MODIS), the Breathing Earth System Simulator (BESS), and the global OCO-2-based solar-induced chlorophyll fluorescence (GOSIF). The results indicate that GPP values of southwestern China, derived from three products, showed similar spatial distribution patterns. Minor spatial differences were observed between GPP values from MODIS and GOSIF, while significant spatial differences were identified between GPP values from MODIS and BESS. All three GPP products demonstrated consistent seasonal variation patterns, with the minimum and maximum values occurring in December and July, respectively. From early January to early May and from mid-September to late December, GPP values from MODIS were higher than those from the other two products. In contrast, from early May to mid-September, GPP values from GOSIF were remarkably greater than those from the remaining two products. The GPP values of southwestern China showed a distinct upward trend over the study period. Notably, GOSIF yielded the highest ratio of pixels with a significant increasing trend in GPP values compared to the remaining two products. Additionally, despite different magnitudes, GPP values from the three products showed similar trends under varying terrain, with relative uncertainty decreasing in the order of GOSIF, BESS, and MODIS. These findings provide a reference for gaining a deep understanding of the performance of different models, thereby offering a scientific basis for determining the carbon sink potential and formulating reasonable pathways for southwestern China.