Abstract: Kochia sieversiana is an alkali-tolerant annual herb belonging to Chenopodieceae. Based on data measured in tow growing seasons, the density-dependent rule of different quantitative characters and the mechanism of quantitative regulation on the natural population of K. sieversiana in the alkaline meadow in the Song-Nen Plain of China were analysed in this paper. The mergence equations of power function that were simulated by sampling two growing seasons were the best descriptive models describing the density-dependence of the population characters, including mean weight per plant, mean fruit weight per plant, fruit weight per unit area, fruit weight/above-ground biomass ratio in the ripening stage. The results of our comprehensive analysis showed that the carrying capacity of environment varied with habitat conditions, and that both the carrying capacities of environment and the effects of density-dependence were larger in the ripening stage than in the flowering stage in the two seasons. The effect of density-dependence was a process of chain reaction. The population regulation was lastly realized by reproductive strategies which increased or lessened energy allocation to the reproductive growth.