Abstract:Based on the density theory of plant growth and related biological hypotheses, the author proposed a new empirical model describing the natural thinning process in an even-ages plant population, i. e. 1/ρ=α(lnω-lnω0)β+1/ρ0 where ρand ω is population density and weight mean plant,ρ0 and ω0 is the initial population density and initial plant weight reapectively, and α and β are parameters. It is proved that the model fits observed data from woody and herby plant density/growth experiments very well, and which is very simple. Therefore it is very useful in practice. Discussing the features and meaning of the model, it is found that the growth process of plants shown in the model is a kind of the Gompertz Curve.