The invention provides a gantry crane travelling unit device for the railway. A motor is arranged at an outer side of a casing. An output end of the motor is arranged in the casing. The output end of the motor is provided with a small bevel gear. The small bevel gear is in a meshing drive connection relationship with a large bevel gear in the casing. A transmission shaft and a travelling axle are installed in the casing. The large bevel gear is installed at one end of the transmission shaft and a transmission gear is installed at the other end of the transmission shaft. A travelling wheel is installed on the travelling axle. A travelling gear is directly or indirectly connected to the travelling wheel. The travelling wheel is in a drive connection relationship with the transmission shaft by the transmission gear and the travelling gear meshed with the transmission gear. The casing is provided with a hydraulic braking cylinder. A power output end of the hydraulic braking cylinder is connected to a brake shoe. The brake shoe which presses the marginal surface of the travelling wheel thereby braking the travelling wheel is arranged at an upper side of the marginal surface of the travelling wheel. The gantry crane travelling unit device has the advantages of compact structure, no strict requirements on a total framework structure of a gantry crane, strong generality, travelling safety and parking reliability.