The location of vehicle-borne mobile mapping system (VBMMS) base on dead reckoning can effectively resolve the problem of the global navigation satellite system (GNSS) outages. Whereas, due to the accumulation of dead reckoning error, the VBMMS may result in large systematic positioning errors and serious impact the final mapping accuracy when acquiring the space three-dimensional (3D) information. In this paper, the simultaneous localization and mapping (SLAM) is proposed to correct the location of VBMMS. The accurate feature extraction from the laser cloud points is the prerequisite for the robotic simultaneous localization and mapping. Considering the structure of indoor environment, a line feature extracting method based on the angle threshold is proposed. The novel method is implemented in the self-developed vehicle-borne 3D acquisition system and the experimental results demonstrate the validity of this method.