The invention is an on-line automatic test system for vehicle driving running deviation, wherein the structure is that a test road section of the vehicle driving running deviation is provided with at least three test points, and each test point is arranged with a test device. The device comprises a portal-type frame, an imaging sensor and a sensor controller which are mounted on the central portion of the portal-type frame, a group of opposite-type photoelectric switches and a test control room. The opposite-type photoelectric switch comprises a photo-emissive tube and a light-sensitive tube,the test control room is provided with a computer which is connected with the imaging sensor through a fiber-optical Ethernet network, and the image sensor controller is connected with the light-sensitive tube through a signal wire. The invention has the advantages of high test efficiency, high test accuracy, high automatic process and the like, and the test result can not be influenced by the technical level of automobile testers.