<p>Welded steel tubular joints have been widely used in bridge engineering, but fatigue cracks are common in the joints under cyclic loads due to structural discontinuity and manufacturing defects. The formation and development of cracks have a great influence on the bearing capacity of joints, and even lead to the lack of safety of joints, thus the normal use of joints is affected. In this paper, for the cracked tubular K-joints under fatigue load, the change of stress intensity factor (SIF) before and after reinforced with carbon fibre-reinforced polymer (CFRP) is discussed by numerical simulation. The influence of the number of carbon fibre-reinforced polymer layers on the SIF of the reinforced joints is also discussed. The numerical simulation results show that the SIF can be effectively reduced by using CFRP to strengthen joint, and the fatigue performance of the joints can be greatly improved.</p>