Abstract: Resource allocation strategy is one of the important contents in the study of plant life history, while the resource allocation between flower size, flower number, and plant size has a close relationship with habitat. By using the method of sampling site investigation, this paper studied the relationships between the flower size, flower number, and plant size (aboveground biomass and plant height) of Stellera chamaejasme population in degraded alpine grasslands at four different altitudes on northern slope of Qilian Mountains, Northwest China. With the increase of altitude, the aboveground biomass, plant height, and flower number of S. chamaejasme population declined gradually, but the reproductive allocation and flower size increased gradually. Along the altitude gradient, the flower number had a significant positive correlation with aboveground biomass (P<0.01), but less correlation with plant height (P>0.05). The flower size had less correlation with aboveground biomass and plant height (P>0.05). The results demonstrated that the flower number of S. chamaejasme population had a significant dependency with aboveground biomass. It was observed that habitat had significant effects on the dependency among flower size, flower number, and plant size. High-altitude environmental stress induced the decrease in plant size. The S. chamaejasme plant ensured its population reproductive success via the resource allocation strategy of increasing flower size and reducing flower number.