The invention discloses an alarm device for a tunnel type computer car washer. The alarm device comprises a car washer rack and an alarm device main body arranged at the bottom of the car washer rack,a connecting wire is arranged at one side of the alarm main body, and two L-shaped ejector blocks are symmetrically arranged on the top surface of the alarm main body; the fixing bases correspondingto the L-shaped ejector blocks are fixed to the bottom surface of the car washer rack, and two L-shaped inserting grooves matched with the L-shaped ejector blocks are formed in the fixing base. By arranging a fixed seat, the L-shaped ejector blocks, the L-shaped inserting grooves, a spring slot, a telescopic clamping rod, a limiting clamping rod slot, a pull rod, a transverse pull block, a rectangular pull block slot, an ejector rod, an ejector rod slot and a pull handle, the mounting mode of the alarm main body is firmer, the problem that the alarm main body in an original device has a certain falling risk is solved, and meanwhile, when the alarm main body needs to be disassembled subsequently to be overhauled and replaced, the alarm main body can be disassembled and assembled quickly.