For the bus has serious impact on the intersection running effective, the paper gives a new passenger car equivalent method for the bus according to the bus's time-space characteristics. When the bus arrives and departs the intersection without stopping, the passenger car equivalent is set as the section of highway, when the bus passes the intersection experiencing stop, the passenger car equivalent for the bus considering some factors, such as the bus's stop space between the stop line, the bus's starting-up characteristics and the bus's impact on the vehicle's behind it, then the bus's passenger car equivalent is given. Through the example using the simulation methods, the different passenger car equivalent of the bus is tested, and it is proved, the methods given in the paper can decrease the vehicle's delay at the signalized intersection.