The present invention discloses a cell reselection method in idle mode of broadband wireless access system. A base station broadcasts a neighboring cell broadcast massage periodically, the massage includes the frequency point, physical code and modulation information of the neighboring cell of the service cell; a mobile terminal receives and updates the neighboring cell broadcast massage, searchesa cell having the required channel quality according to the frequency point list of the neighboring cell carried in the neighboring cell broadcast massage when the cell needs to be reselected, receives and analyzes the DLMAP information of the cell and finishes the cell reselection. In the invention, the prior information of the neighboring cell is obtained via the neighboring cell broadcast massage, so as to guide the mobile terminal to search the uplink channels in a certain scope; the physical code and modulation information of the new cell is obtained according to the neighboring cell broadcast massage, omitting unnecessary time for receiving physical code and modulation information; the MAC synchronous process is simplified, thus saving the time of the mobile terminal in wake state,reducing the power consumption of the mobile terminal and extending the use time of battery.