Abstract: This study investigates the effects of post weld impact treatment of spot welding on the mechanical properties and fatigue characteristics of the spot welded joint. The impact treatment process generates the compressive residual stresses in resistance spot-welded low carbon steel using two different impact treatment process using a specially designed Low Blow Impact Treatment (LBIT) apparatus and Pneumatic Impact Treatment (PIT) equipment. LBIT impact energy of 6 Joule and PIT using air pressure of 4 bar were applied to the welded joint. The effect of the impact treatment on mechanical properties of the spot-welded joint was investigated. Assessments of the mechanical properties and qualitative results between as-welded samples and the post weld impact treatment samples have been examined. Fatigue test was also conducted to evaluate the fatigue characteristics of spot-weld joint. The tensile-shear load of RSW PIT exhibits the highest value (8.81 kN) as compared to the RSW LBIT (8.42 kN) and RSW as-weld (8.20 kN). The fatigue life of RSW PIT was more than 4 times longer than those of as-weld samples throughout the whole load range. While, the fatigue life of RSW LBIT was 3 times longer than as-weld samples. Results showed that an improvement in the mechanical properties and fatigue strength has achieved through the post weld impact treatment.