Steel is a metal that commonly used in fabrication, engineering, and reparation activities in the structure construction industry. ASTM A53 steel is a low carbon steel with 0.25% to 0.3% of carbon content so it has a high weldability. ASTM A36 steel is a low carbon steel with carbon content of 0.25% to 0.29% and is often used in the floating building industry. This study aims to determine the effect of shielding gas flow rate and V-groove type to the tensile strength of A53 steel welded with A36 steel by Gas Metal Arc Welding (GMAW) method. The shielding gas level used is 100% CO2 with flow rate variations, including 15 liters/minute, 20 liters/minute, and 25 liters/minute. The groove types used are Single V-Groove and Double V-Groove. Tensile strength test result showed that in the welding process in this study, specimen with 25 liters/minute flow rate on the Double V-Groove had the highest