The invention relates to a direct connection structure of an engine, a generator and a hydraulic pump in a mobile welding workshop. The direct connection structure comprises the engine, the generator and a hydraulic pump set, which are disposed in sequence. An output shaft of the engine is directly correspondingly connected with an input shaft of the generator. An output shaft of the generator is directly correspondingly connected with an input shaft of the hydraulic pump set. Power generation and hydraulic travel drive of the mobile welding workshop can be integrated by the direct connection structure of the engine, the generator and the hydraulic pump. The direct connection structure is simple in drive, high in drive efficiency and stable and reliable in operating performance, energy consumption and failure rate of the mobile welding workshop can be reduced greatly, occupied space is small, and the overall size of the mobile welding workshop can be reduced.