Spatial heterogeneity, which is one of the basic characteristics of ecological and geographical elements, is substantial in mountainous areas. Research on ecosystem services (ESs) increasingly considers spatial heterogeneity in environmental management-related decision-making. This study quantified the dominant ESs and ES trade-offs for the Hengduan Mountain region in Southwest China. The spatial heterogeneity was analyzed by introducing gradients of elevation, vegetation cover, and land cover. The results showed that, in addition to inverse changes in ESs, ES change rates were important for ES trade-offs. Further, land cover was identified as the main factor influencing the spatial heterogeneity of the majority of ES trade-offs. Specifically, the net primary productivity (NPP), carbon storage (C), and habitat quality (HQ) all showed inverted U-shaped trends along the elevation gradient and HQ increased thereafter, water yield (WY) presented an overall decline but increased in high-altitude areas, and soil conservation (SC) exhibited a fluctuating trend. The change rate of SC was slower than that of NPP, C, and HQ, which led to changes in the trade-offs between SC and other ESs along the elevation gradient. The higher WY in built-up land and higher HQ in forests were the main reasons for higher trade-offs. The low trade-off for unused land was attributed to the limited levels of several ESs. Along the vegetation gradient, WY first decreased then increased, whereas all other services showed increasing trends. The limited promotion effect of vegetation on SC was the primary reason for increased trade-offs. Therefore, more attention should be devoted to improving SC via engineering measures. Furthermore, vegetation degradation on unused land should be prevented to maintain SC and reduce the trade-offs among ESs.