Abstract:Plant biomass-density relationship (B-D) has been one of the hot spots in ecology. Since Yoda′s the -3/2 power law of self-thinning, studies focusing on B-D relationship in plant ecology have been conducted to elucidate the variability of self-thinning line and the effects of environments. The recent developed WBE model that the metabolic theory of ecology was applied to self-thinning law arose highly debates. The major questions addressed were whether slope of self-thinning line (α) is constant (-3/2 or -4/3) and how environment influences B-D relationship. In this paper we reviewed recent researches on -3/2 self-thinning law, -4/3 self-thinning law, isometric scaling of biomass-density and effects of environments on B-D relationship. It suggested that B-D relationship under stress environment and mechanisms of B-D relationship needed further studies.