Soil organic carbon turnover depends heavily on the composition of particulate organic carbon (POC) and mineral-associated organic carbon (MAOC). However, the dominance of MAOC and POC is controversial, especially in the high-altitude cold regions, limiting our ability to predict changes in soil carbon pool. Here, by conducting field surveys along a 2900 km transect across alpine meadow, steppe, shrubland, forest and wetland, and synthesizing 592 sampling data in the Qinghai-Tibet Plateau, we present the divergent patterns and drivers of POC and MAOC with different aridity index. Results show that MAOC contents account for 66.5 % and 58.4 % of total SOC in arid and semi-arid areas, whereas POC dominates in humid and dry sub-humid soils with the proportions of 62.9 % and 52.5 %. Nonlinear relationships are observed in the responses of POC and MAOC to aridity within the threshold of 0.59. We find that total nitrogen is the primary drivers of MAOC and POC regardless of aridity, and high aridity exacerbates the negative effects on SOC fractions. Our findings highlight the discrepancy in the dominance of POC and MAOC with different aridity levels, which provide essential mechanism for superiorly predicting alpine soil carbon-climate feedback.