Under the given economic environment，this paper studies the equilibrium model of supply and demand among self-owned house buyers，investors，and developers． By comparing with the housing market with rigid demand，it is found that the speculative behavior of investors is an important factor affecting the change of housing prices． In particular，extrapolative investors have a boosting effect on the trend of housing prices，and mean-reverting investors not only have a stabilizing effect on the market but also increase the market complexity． When there is an interaction among different trading agents in the housing market，housing prices will deviate from their benchmark price，depend on their paths，fluctuate hugely，and fall into the trap of low housing prices． The government can regulate the housing market by adjusting basic economic variables such as down payment ratio and development cost． Compared with the down payment ratio regulation，the development cost adjustment not only can adjust the benchmark price，but also can change the impact of investors’behavior on housing prices and play a comprehensive role in adjusting the market． Therefore，the development cost adjustment is more effective than the down payment ratio regulation．