Information, as a key factor of determining the efficiency of securities market, essentially takes play an important role in the economic function of the securities market. How to solve information asymmetry problem and to make securities market from ineffective market towards effective market, is the basic goal of the institution design and the basic way to promote efficiency in the securities market.This paper structures the information transmission model of securities market through borrowing the information transmission model in common use. Passing the description and definition of information source, channel and user in the securities market, the paper has studied the constitution of the securities market information subject and the principles of information transmission; The behavior characteristics of the supply and demand in the process of securities market information transmittance have been discussed , and the causes of the information asymmetry of securities market have been probed .In this paper, we put forward three kinds of origin causes which forming the information asymmetry of securities market: Firstly, the information asymmetry produced on the basis of the information source , including: the alternative disclosure of information , the disclosure of information not in time, the false disclosure of information. Secondly , the information asymmetry on the basis of the channel transmit process, including: delayed by the space-time transmitting channel , by the means of technological and information variance (including, benign-variation and malignant-variation). Thirdly, the information asymmetry on the basis of the user's ability. Above-mentioned sort research shows that the information asymmetry exists eternally which determined by the characteristic and behavior of information source, channel and users abilities among the information transmittance process. In this paper, we also set up the investment pricing model and the game theory model between disclosure of information and supervision under the information asymmetry of securities market .Studies have shown that it is still the most efficiency method to increase check probability, strengthen punishment to false disclosure of information and strengthen the prestige mechanism construction of