The invention discloses a method for reinforcing a steel tube truss tubular joint through ring opening sleeves. The two semicircular sleeves are adopted in the method, an orifice matched with the position where a reinforced joint main tube intersects with a reinforced joint branch tube is formed in the middle of a straight-line side of each sleeve, and the two orifices are in butt joint to form a round hole; the reinforced joint branch tube is welded to the reinforced joint main tube, and a T-shaped tubular joint is formed; the two sleeves are respectively and oppositely clamped onto the reinforced joint main tube, and the two orifices are oppositely clamped onto the reinforced joint branch tube; the two sleeves are in butt joint to form a welding seam, the upper surface of the welding seam and the lower surface of the welding seam are in butt joint, the two orifices and the surface of the reinforced joint branch tube are welded to form a surrounding welding seam, and the two sleeves are connected to the reinforced joint main tube in a sleeved mode to form two lateral welding seams. According to the method, the static performance of the tubular joint can be improved effectively, the anti-seismic and anti-fatigue performance of the joint can be improved effectively, and therefore it is guaranteed that a tube truss structure has higher bearing capacity, better anti-seismic performance and longer service life.