A cruise control method of a mild hybrid electric vehicle may include determining whether a cruise mode is operated according to an output signal of a user interface device by a controller; determining whether a vehicle speed increasing signal is output from the user interface device by the controller; determining a compensation torque depending on difference of a predetermined target speed and the current speed of the mild hybrid electric vehicle according to the vehicle speed increasing signal by the controller; and controlling the operation of the MHSG by the controller to output the determined compensation torque.