Abstract: This paper sets up a model to examine how the irrational trading behavior such as overreaction and underreaction, optimism and pessimism significantly affects the short price behavior of financial asset. The comparative analysis of the simulated results indicates that even if the information in financial market is symmetric, the financial asset short-term price behavior is significantly different when a greater proportion of irrational traders exist in the market. The financial asset short-term price is more volatile when the irrational trading behavior is more serious.