The assessment system and method of sustainable development of human-earth system and the sustainability of human-earth system in Shenzhen and Dongguan, the rapid economic area in Guangdong province were studied in this paper. The principles that combine the space and time , relative simple and regional classification should be in mind when the assessment system is formulated. The calculating fomulas for sustainability of human-earth system and coordinate coefficient between social-economic development and the state of environment , natural resources were put forward. 16 assessment factors of social , economic , natural resources and environment were sellected and the criteria of sustainability assessment was posed. The sustainability of human-earth system are dependent on not only the development level of society and economy, the state of resources and environment, but the coordination degree between two aspects. The assessment results show that the developmental sustainability was risen gradually from 1980 to 1990, but descended after 1990 in Shenzhen, and that was risen gradually from 1980 to update in Dongguan. Two regions are weak in the state of developmental sustainability recently, but that in Dongguan is slight better than in Shenzhen. The descent canse of sustainable development state of human-earth system in Shenzhen are that the environmental quality became worse and the consuming rate of natural resources was too fast. The countermeasures of rising the sustainability in Shenzhen are increasing the investment in environmental protection and increasing thd natural resources utilization efficiency.