The invention discloses a method and a system for three-dimensional laser scanning sectional measurement of tunnel engineering. The method comprises the following steps: obtaining a tunnel scanning range and a survey station location list, wherein the survey station location list comprises location information of a plurality of control points sequentially along the axial direction of a tunnel; determining the location information of the first control point in the station location list as the location information of the current survey station location; adjusting a test instrument according to the location information of the current station location; controlling the test instrument to scan two sides corresponding to the axial direction of the tunnel according to a rectangular area scanning technology and perform scanning according to a panoramic scanning technology; and determining the location information of a next survey station location corresponding to the current survey station location in the survey station location list as new location information of the current station location after the scanning is completed until the scanning of the tunnel scanning range is completed. The method and the system, using the sectional combined rapid measurement technology, have the advantages of high data utilization rate, fast measurement speed, and fastness and simplicity in data processing.