To realize healthy and sustainable development of cities, urban planning must be under the direction of environmental ethics and form scientific view of development. The necessity of introducing environmental ethics into theory and practice of urban planning and urban construction shows up in following three aspects: first, there is close relationship between environmental crisis and urban development and planning; secondly, there is value prejudice in solving urban environmental issue for urban planning; thirdly, there is need for development and innovation of urban planning and environmental ethics.