The thesis discusses the NGO's function of social, economic and political. And discusses the NGO's developing background of society, economics and politics.And discusses the relation of the NGO and market, government, middle class and mass media.Chapter one expounds the social background of NGO developing, which includes the failure of market, government, social ethics and the history of NGOs. Analysis NgO's developing trends and the NGO's function in society and economics these years .at present, western scholarships and political leaders are probing into the social parternership between government, enterprise and NGOs.Chapter two expounds the developing history of NGO, and analysis the different times of NGO's developing in Middle Ages, model times and up-to- date. NGO's function in middle ages is social relief and social charity. At modern times, NGO's function evolving from church charity into secular charity. And the traditional charity evolved from simple social relief into educational relief.And modern government takes on more and more responsibility in social relief and social welfare.Up to date, NGO is developing fast in 70years in 20th century, which background of the failure of market and government in recent years in 20th century. Ngo partakes in every field in such social relief, education and environmental protection today. Chapter three analysis the relativity of the market and NGO. First the thesis tells NGO rely upon market, which provides foundation for NGO. Second the public includes pollute and middle class take part in public welfare that illustrate there is relative coefficient between the NGO and market and their efficient is 0.66.Third, the thesis tells the story of market institution including the constitution of property protection, the rival rule of property and the property distribution.Chapter four analysis the relativity of the democracy and NGO. Democracy provides political foundation for NGO.Democracy is an important measure to avoid the corruption of government. And democracy is a key to set up social partner between NGO and government.