The problem of biological allometric growth relationship has always been a hot issue in ecology. The allometric equation is usually expressed in the form of a power function of metabolic rate and body size. This paper reviews some theoretical models of allometry, including self-similar fractal-like distribution network model, metabolic theory of ecology model and energy consumption model. The metabolic rate of an individual affects the ecological processes at different levels of ecology, and can be applied to individuals, populations, communities, and ecosystems. The application of the allometric models on three different scales of individual, population, community and ecosystem are introduced.