According to duopoly trading under incomplete information，the insider trading model in risk assets transaction market is proposed. The insider traders can obtain private information，therefore，the insider traders can obtain profit by using the private information to invest，however，after the insider traders analyze the advantageous situation of the market，they input trading volume by risk probability，then the trading strategy of the insider traders is the same，they expect higher profit and bigger transaction strength，but the released private information is unchanged. Because the insider traders can selectively input the total，they input large trading volume when the trading volume is favorable to them，thus，their transaction strength is bigger，they can obtain high profit. The released amount of private information of the insider traders is only related to trading volume and is nothing to do with whether they join the transaction. As a result，it is more favorable for the insider traders to selectively input trading volume.