The joining process using the method of spot welding of dissimilar metal materials has been carried out. The use of welding voltage and time variations will affect the quality of the results of the welding connection itself. Setting the voltage parameters and the right welding time will produce a good connection quality. The purpose of this study is to determine know the influence of variations in voltage and welding time on tensile strength, hardness values and microstructure of copper and stainless steel 304 joints. The voltage variations used are 2.02 V and 2.30 V and the time used are 4 seconds, 5 seconds and 6 seconds for each voltage variation. Test specimens using copper and stainless steel 304 material with a thickness of 1mm each plate and a length of 100 mm x width 30 mm. This research uses lapjoin type with copper position above and stainless steel 304 below. The results of microstructure testing show that the effect of stress variations and welding time causes changes in grain size to be greater in the HAZ and weld metal regions. The highest hardness values are in the weld metal area, namely: ± 79.1 HV in copper and ± 240 HV in stainless steel 304. The highest value of the tensile load capacity is at 2.30 V voltage and 5 seconds with a value of 1.2 kN and the value of the tensile load capacity -the lowest shift is at a voltage of 2.03 V and a time of 6 seconds with a value of 0.37 kN, meaning that the higher the applied voltage, the higher the drag load capacity will be. The variation parameters of welding stress and time greatly affect the value of tensile load, microstructure and hardness.