This paper demonstrates the optimization of resistance spot welding on different connections of galvanized steel sheets and low carbon steels. The zinc coating on galvanized steel sheets will have an effect to reduce the welding ability in the resistance welding process. The practical Taguchi experimental technics were used by implemented adequately to optimize input factors, namely squeezing time, welding current, welding time and holding time. Statistical software implemented an analysis of variance (ANOVA) and multilinear regression to investigate and evaluate the significant input factors and compare them with the experimental output factors of resistance spot welding. The 'signal to noise ratio' (S/N ratio) results shows that the welding time and the welding current are the most significant factors on the output. The delta values ​​of welding time and welding current are 3.15 and 2.25, respectively. The ANOVA results showed that welding current and welding time are the most contributing factors by 23.5% and 51.4%, respectively. Taguchi recommends an optimal squeezing time of 20 cycles, a welding current of 27 kA, a welding time of 36 cycles, and a hold/cooling time of 15 cycles. The highest output reaches a tensile shear strength of 5762.04 N on the third iteration. The present research has successfully identified significant variable inputs for resistance spot welding, namely welding current and welding time. In the future, the relevant research may use our corresponding results to improve the RSW practical procedure for other significant impacts.