To solve the GPS denies or no GPS positioning problem of the vehicle-borne mobile mapping system (VBMMS), a fast simultaneous localization and mapping (SLAM) method using the horizontal 2D laser scanner and the odometer is proposed. Through position error analysis of VBMMS, the scientific prediction and re-prediction parameters are set. An improved extended Kalman filter (EKF) based on wide-interval prediction and re-predition are presented to speed up. The experiments done in the closed corridor show the method mentioned above are reliable.