Abstract: In order to solve the welding problem of high strength steel sandwich plate, a welding method of flux bands constricting arc welding (FBCA) was proposed, and a well-formed T-joint is obtained. Firstly, the melting state of flux bands at high temperature is measured and analyzed. Secondly, The high-speed camera system was built to collect the arc and droplet images in the welding process, analyze the change of arc morphology and droplet transfer mode. Finally, measure the size of the welded T-joint and study the forming rule. The results show that under different parameters, FBCA welding has short circuiting transfer, arc bridge transfer, globular transfer, fine transfer and meso-spray transfer. The flux bands has small particle, large particle, liquid bridge and arc bridge coexistence. When the flux bands is in the form of arc bridge or liquid bridge, and the arc bridge transfer, the arc is compressed and burned stably, and the weld forming is best.