Abstract: Welded joint specimens of high-strength structural steel with thickness of 48 mm were prepared by the welding method of SMAW. The fatigue crack threshold ΔK_th, fatigue crack growth rate da/dN and fracture toughness K_IC of welded joint affected zone and base metal were researched and the performance contrast was analysed. The results showed that the welded joint heat affected zone had better performance on fatigue and fracture. With the increase of distance from fusion line, the microstructure of heat affected zone was coarse lath bainte and austenitic film, fine granular bainite, fine granular bainite and tempered sorbite, and the hardness dereased gradually. The impact energy of the two sets of specimens were on the upper platform at room temperature. The residual austenite film and bainite with higher hardness were the main factors that affected the performance of joint.