In order to solve the problem of easy oxidation and welding difficulties of LZ91 Mg-Li alloy, a four-layer hollow structure component with good joint performance and adhesion degree was prepared, and the influences of dipping time and brazing temperature on the joint performance were studied by means of ultrasonic assisted dipping copper coating method. The results show that with the increasing of dipping time and brazing temperature, the shear strength and bonding degree of solder and base metal increase first and then decrease. When the dipping time is 2 h and the brazing temperature is 260 ℃, the shear strength of welded parts is the highest. According to the optimal process parameters, the LZ91 Mg-Li alloy plate is conducted by superplastic forming, the core plate and panel are prepared and connected respectively, and the final LZ91 Mg-Li alloy mixed grid four-layer hollow structure components were obtained with good shape. Thus, the experiment effectively solves the problem of easy oxidation for LZ91 Mg-Li alloy during the connection process, which has important reference significance in the manufacture of high performance and lightweight structural components.