The invention relates to an integrated-type steel structure roof photovoltaic system. The integrated-type steel structure roof photovoltaic system comprises main beams, secondary beams, pieces of angle steel, purlines, supporting blocks, electric weld pieces, assembly frames, pressing blocks, pressing strips, sealants, waterproof adhesive tapes, color steel tiles, lateral cover plates and photovoltaic plates. The secondary beams are vertically erected on the two sides of the main beams correspondingly, the main beams are each in a U shape, and the two sides of the main beams are provided withmain beam shoulders, wherein the directions of the main beam shoulders are inward. Semicircular notches are pressed in the main beam shoulders, and the pieces of angle steel are welded to the outer sides of the bottoms of the main beams correspondingly and connected with the purlines through first screws. The integrated-type steel structure roof photovoltaic system has the beneficial effects thatthe main beams with the U-shaped sections, the inverted-T-shaped supporting blocks and certain compression components are adopted to constitute the integral mounting system, on-site construction is easy and convenient, materials are saved, and the roof water discharge is also greatly increased; and compared with a traditional building photovoltaic integrated system, the main beams are fixed to thepurlines through the pieces of angle steel on the outer side, inner cavities of the main beams do not need to be punched through, and water in the main beams is prevented from entering a building.