It is a common subject in the world with the development of economy and society and the deepening of reform in the field of public service to enhance the mechanism recreation of public service's offering system and to provide more fair, effective and fast public service for the public. The public in China, a developing country with changing in nature, have increasing needs to the public service and the government. At the same time, the government is facing the new challenge to improve public service offering ability with the perfecting socialist market economy system and constructing a better-off society.The author, taking the government public service of our country as an object, analyses the present situation and existing problems of the government public service offering. The author refers to the successful experiences of foreign countries, explores the government public service offering mechanism available for China and suggests constructing a balanced, fair and square-led public service system.In the author's opinion, the key reason for the low-leveled, unbalanced and low-effective public service is imperfect mechanism of institution which makes decision not reflect public needs, the offering pattern unitary, the offering vacant, offside and dislocated and lacks system of investigating liabilities and estimating performance. Therefore, the author tries to design a scientific public service offering pattern on the basis of the present situation of China and the characteristics of Chinese public service to meet increasingly complicated and variable wants of the public. The author constructs an analysis structure with the core of institution mechanism of public service and focuses on exploring decision-making system, efficiency system, fairness system and system for stimulating staff initiative.Now, there exists two misunderstandings about the subject of public service: the one is that economy increasing can guarantee public service; the other is that market can adjust public service. The author points out that the effective attribution of development result should be adjusted by effective public service mechanism. Market economy can improve efficiency and provide more private products, but it often doesn't work in the field of public service. So, government should be the subject of public service. Government must change in nature, strengthen its service function and provide basic public service and products to realizeequality of basic public service. In the present stage, government's leading role in public service offering should be emphasized .In the paper, the institution mechanism of public service is a set of dynamic systems and a series of system arrangement which regards government as a leading role, takes offering basic public products as a main task and the public sharing reform results as a basic goal. The establishment of the mechanism is to realize public resources'optimal disposition through the power of the Party and government, to overcome some defect of market economy to realize fairness and efficiency of public service offering.