Metal roof structure and construction method thereof

The invention relates to a metal roof structure and a construction method thereof and particularly relates to a primary purline structure for a metal roof and a construction method of the primary purline structure. The primary purline structure of the metal roof comprises primary purlines mounted on a main structure, a bottom plate mounted on the primary purlines and secondary purlines mounted on the bottom plate. U-shaped grooves are formed between the primary purlines and the bottom plate, two ends of the U-shaped grooves extend outwards respectively to form connection plates, and the U-shaped grooves are attached to and connected with the primary purlines through the connection plates. The secondary purlines, the bottom plate and bottoms of the U-shaped grooves are fastened through self-drilling screws. According to the metal roof structure and the construction method thereof, the U-shaped grooves are arranged between the primary purlines and the bottom plate on the primary purlines, so that the thickness