The invention discloses a detection method of a tunnel maintenance vehicle with an alarm function, and belongs to the technical field of engineering machinery. The tunnel maintenance vehicle comprises a headstock, a maintenance lifting platform and a compartment, wherein the maintenance lifting platform is installed between the headstock and the compartment. Based on the structure disclosed by the invention, a maintenance system and an information acquisitions system are arranged additionally. The maintenance system comprises a control cabinet, a display screen, a front distance sensor, a rear distance sensor, a rotary bearing mechanism and detection devices, wherein the rotary bearing mechanism comprises a rotary bearing base, a rotating motor, a rotating shaft and a rotating support; and the detection devices are installed on the rotating shaft through bearing bushes respectively. The information acquisition system comprises a universal rotating bracket, a 3D holographic scanner and an information storage module. By adopting the detection method, an area, where cracks appear or a surface layer falls off, on the inner surface of a tunnel can be detected automatically and quickly, regional 3D information acquisition is conducted on the tunnel while quick maintenance is achieved, a basis is provided for later-stage work, and then the maintenance efficiency and information acquisition and maintenance effects are improved.