The invention discloses a pipe segment splicing cabin structure for segmenting prefabrication of an underground pipe gallery. The pipe segment splicing cabin structure comprises a splicing cabin body. A gantry crane is arranged above the splicing cabin body and comprises a pipe segment discharging device which can be perpendicular to discharged pipe segments. A pipe segment splicing platform which corresponds to the pipe segment discharging device and can support pipe segments to be spliced is arranged inside the splicing cabin body. The periphery of the pipe segment splicing platform is provided with an oil cylinder which can extrude the pipe segments to the inner side. The bottom of the rear end of the splicing cabin body is provided with a guiding hole through which the pipe segments can penetrate. The pipe segments are convenient to splice, can be widely applied to pipe gallery building construction of various open cutting modes, the pipe segment conveying difficulty and the pipe gallery construction cost are lowered, and the pipe segment splicing precision is improved.