Abstract: Laser welding-brazing joint lap tests were carried out on AZ31B magnesium alloy plate and TC4 titanium alloy plate with Ni sheet as interlayer. The mechanical properties, interface macro morphology and microstructure of the joint were analyzed. The results show that the welding zone of Mg/Ti laser welding joint with Ni as intermediate layer is well formed, and scale lines appears in some positions, the weld zone consists of magnesium side weld zone, titanium side weld zone and interfacial compound layer (IMC). The IMC layer on the magnesium side zone is composed of Mg-Al-Ni phase and Mg₂Ni phase, and the IMC layer on the titanium side zone is composed of Ti₂Ni phase. With the increase of welding heat input of joint, the elements in both sides of the weld zone are fully diffused, and intermetallic compounds are formed in both sides of the weld zone, which greatly enhances the mechanical properties of the joint. With the increase of welding heat input, the penetration of titanium side increases all the time, and the tensile shear load of the joint first increases and then decreases. When the welding heat input Q = 722.22 J·cm⁻¹, the tensile shear load of the joint reached 1241.67 N.