Abstract: The actual layout of town greenbelt issummarized briefly.In the meantime，The fact that environmental afforestation in towns must follow the ecological principle is discussed from nine aspects，i.e.the ecological characteristics of species，the relationships among the species，community structure，community succession，edge effect，biodiversity，ecological invasion，genetically modified organisms and antipollution.Finally，it is indicated that the precondition of achieving optimal eco-efficiency in town afforestation is to apply the ecological principles in marking out town greenbelt and designing the community of town greenbelt.