The utility model relates to the technical field of building structures, and discloses a building steel structure net rack which comprises node balls and connecting rods, mounting holes are formed in the side walls of the node balls at intervals, adjusting grooves are formed in the node balls, and the mounting holes penetrate through the wall faces of the corresponding positions of the node balls and are communicated with the interiors of the node balls. According to the utility model, when the steel structure net rack is assembled, only the plurality of connecting rods need to be inserted into the adjusting grooves of the node balls, then the adjusting rods are screwed, and the adjusting rods can vertically descend due to the threaded connection of the adjusting rods and the adjusting holes, so that the connecting rods can be assembled into the adjusting grooves of the node balls, and the connecting rods can be assembled into the adjusting grooves of the node balls. The limiting plate is driven to descend under the limitation of the fixed block and the movable disc, so that the clamping plate on the limiting plate is quickly and accurately buckled in the clamping groove of the connecting rod, connection is completed, the connection mode is easy and efficient to operate, and compared with a traditional complex connection technology, the construction time is greatly shortened, the construction efficiency is improved, and the labor cost is reduced.