Abstract: Using original welded joint and once-repair welded joint of 30CrMnSiA high strength steel as research objects, the influence of repair welding on mechanical properties of the welded joint was studied by tensile test, fatigue test and microstructure analysis. The results show that the mechanical properties of the welded joint were slightly degraded after repair welding. The weak part of the welded joint in tensile property was heat affected zone while that in fatigue performance was welding toe. The repair welding had little influence on the microstructure around the welding seam.