Abstract: The influence of Leymus chinensis population density on growth dynamics at modular level was investigated. The correlation between density and growth dynamics of single experimental L. chinensis was analyzed. The results were as follows:① Genet’s density influenced ramet’s density and developmental process. Adjusting genet population density can narrow the variation range of ramet density. ② The population biomass increased as density increase, but it did not come to a constant value. But the biomass per genet began to decrease as density became bigger. ③ Under low density, vegetative propagation dominated and survival capacity of rhizome buds was high while sexual reproduction dominated and the reproduction allocation value was big under high density.