Floral display plays a vital role in attracting pollinators and reproductive success of plants. Theoretical studies show that there is a tradeoff between the size and number of flowers due to resource limitation, which constrains the evolution of floral display. But empirical studies did not frequently detect the tradeoff of flower size and number. This study aims to examine the amongpopulation variation in floral display of Saussurea dzeurensis, which distributes widely in QinghaiTibetan Plateau, and especially to examine the tradeoff of flower size and number at the capitulum and flower levels. The results showed that significantly positive correlations existed between capitulum number per plant, mean capitulum biomass flower number per capitulum and aboveground biomass, indicating that floral display size including the flower and capitulum levels depends on resource condition of individuals. Individuals from the highaltitude population were smaller and produced less capitula, but single capitulum mass, flower number and mass per capitulum did not vary significantly compared to the lowaltitude population. Although there was no tradeoff between capitulum size and number, a negative correlation between flower size and number of the highaltitude population shows a tradeoff between them. However, the tradeoff between flower size and number was not observed in the lowaltitude population. After controlling the effect of plant size, the relationships between size and number at the both capitulum and flower levels did not change, suggesting that the difference of resource acquisition among plants did not affect the tradeoff between the size and number at both flower and capitulum levels of S. dzeurensis. The relationship of flower size and number in plants may be complicated, and studies at population, individual and inflorescence levels will contribute to understanding the resource allocation of flowers and mechanism of flower display evolution.