Abstract: The rapid solidification welding of quenched Cu-Sn alloy foils with the thickness of 40-60μm was conducted by a micro-type capacitor discharge welding machine, and the effects of welding parameters on microstructural morphology and mechanical properties of joint were researched. The results indicate that welding voltage and electrode pressure have obvious influence on the shear strength of joint under fixed capacitance. With the increase of Sn content, the welding voltage needed decreases and electrode pressure rises accordingly. The favorable welding parameters are U=90 V, F=11 N for Cu-7%Sn alloy and U=85 V, F=11.5 N for Cu-13.5% Sn alloy. The main welding defect is porosity. With decreasing of welding voltage and increasing of electrode pressure, the joint cooling rate increases and the pore nucleation rate decreases. Meanwhile, the growth, mergence and migration of porosities are suppressed, resulting in the decrease of porosity forming tendency.