Alpine plants may change their biomass allocation patterns in response to the increasing environmental severity associated with increasing altitude. In this study, we investigated the biomass allocation of 1000 individual plants from 30 genus across 3000 m altitude gradient in Qinghai-Tibetan Plateau. We explored the patterns and determinants of individual biomass allocation along environmental gradients, and especially tested the hypothesis that alpine plants might increase their reproductive effort at high altitudes. The regression analysis showed that, the flower mass fractions of total biomass and shoot biomass have tendency to increase with increasing altitude in about 60 and 76% of studied genus, respectively, and in about 20% of the genus, which are almost the entomophilous plants showed statistically significant increase with increase of altitude. The linear mixed model showed that altitude and annual mean temperature had significant effects on the flower mass fraction when controlling genus and sampling sites. Our results suggested that alpine plants can response to serve alpine environment through changing the biomass allocation, such as increase allocation of biomass to reproductive organs, in particular in entomophilous plants.