The invention discloses a full-automatic laser tunnel section convergence instrument and a measuring method. The full-automatic laser tunnel section convergence instrument comprises a laser ranging system, an acquisition and communication system (2) and a mounting and fixing system (3), wherein the laser ranging system comprises a plurality of laser ranging modules (11); the acquisition and communication system (2) comprises a central processing module, a data acquisition module, a data storage module, a data communication module, a power management module, a power interface (26) and a data interface (27); the mounting and fixing system (3) comprises a pedestal (31), a core plate (32), a frame plate (33), a cover plate (34) and an inclinometer (35); and the laser ranging modules (11) are fixed on the core plate (32), each laser ranging module (11) is connected with the data acquisition module through a data line, and the laser ranging modules (11) and the core plate (32) are arranged within the frame plate (33). The full-automatic laser tunnel section convergence instrument can be mounted on a tunnel vault or side wall conveniently, and achieve full-automatic tunnel section multi-point convergence monitoring and data transmission.