The relationship between flower size and leaf size and number reflects the plant adaptation strategies in external morphology during the longterm interaction of plants with different environments, and the variation of the relationship reflects plant adaptation to heterogeneous environments. In this study, an investigation was carried out to examine the relationship between flower size and leaf size and number of Stellera chamaejasme along four different altitude gradients in an alpine grassland in the northern slope of Qilian Mountains. The results showed that, with increasing elevation, the height, density, and aboveground biomass of the plant communities displayed a pattern of initial increase and then a decline. The aboveground biomass, plant height and leaf biomass of S. chamaejasme declined gradually, while reproductive allocation, flower size and leaf number both increased gradually. Flower size of S. chamaejasme was significantly positively correlated with leaf number (P<0.01), but negatively with leaf biomass, while there was no significant correlation between flower size and leaf biomass (P>0.05). Therefore, habitat had a significant influence on the dependency among size of flower and leaf size and number. The plant size would be decreased by the environmental stress at high altitude, and both flower size and leaf number are increased while the leaf size is declined to ensure the reproductive success of S. chamaejasme.