problems in big cities Something unreasonable shown up these years. Metropolises, which are the signs of civilization, give their dwellers a deteriorating environment of living. Pollutions, high-level pressure and so on became usual. These causes the problem of public health. The overcrowding people in big cities should be the deeper reason. Citizens in 18BC can hardly image why rubbishes from daily life make up of seriously pollutions. They also cannot feel the hardship of asking for cure we meet nowadays, too. To solve these problems, we need help from both the government and our citizens. For government, policies work in reduce fertility can be made. Doing with request of convenient treatment, more hospital should be built, and more doctors should be trained. In the same time, social education in healthy part must be developed. As citizens, we have to cooperate with government’s activities. For example, turn our life style into a healthier one is a good choice. People with high social responsibility are models where we can learn how to be useful in the war fight with pejorative environment caused by overpopulation. Many new trends show ways to protect the prosperity. Such as researching on environmentally friendly resource. Oil and gas keep our society run, but pollutions from flame threaten people’s health. Building Satellite cities and developing urban-rural fringe areas mean people are trying to solve public health problem by ruling the edge of cities again. If these actions work, happiness of living in metropolises will back to our minds, while a new beautiful world can be seen at tomorrow.