| It is generally said that small-and-medium enterprises(SMEs) will play an important role in economic development during the 21 century. SMEs can upgrade economic development,improve market efficiency, optimize industry structure, drive technique innovation, increase employment chance, promote internatonal trade, boost society stabilization. But because of asymmetrical information, faultiness contract, diseconomy scale, big restriction system and so on, It is difficult to finance for SMEs and difficult financing restricts SMEs'development.Information asymmetry theory, which was brought in 1970s, effectively explain SMEs financing difficulty. For one thing, SMEs conside different financing cost, for another thing, financial institution prudently reply to SMEs'demand for avoiding converse option and moral hazard. The text builts SMEs credit and honor model to expatiate the role of information and credit and advances relevant way.The text is made of four part. Introduction describes subject background, research summary, means and structure. First section depicts SMEs conception and actuality. Second section introduces information asymmetry theory , game theory, development finance theory. Third section explains SMEs financing difficulty with information asymmetry theory. Fourth section expatiates SMEs'Suggestion in infomaion asymmetry. |