The current work is all a matter of the separate study of the effect of charge thickness or stand-off gap on the quality of the bonding interface. The relationship among collision velocity, charge thickness and stand-off gap in parallel explosive welding was illustrated. Four TA2/Q235B composite plates with different parameters were manufactured to investigate the effect of the collision velocity on the bonding interface. The interface morphology, element diffusion and mechanical properties of samples with different parameters were discussed, respectively. The results indicated all samples were corrugated combination and the higher-speed samples obtained larger waves with more pronounced vortex regions and melted layers. The composite interfaces presented six different grain structures due to plastic deformation, respectively. In addition, high-speed samples had a wider element diffusion layer. TiFe3 and TiFe2 were found in the vortex region and the melting layer, respectively. The mechanical tests showed that the hardness of the interface was the highest and decreased gradually to both sides. The tensile strength and shear strength were higher than the raw material. The higher collision velocity increased the tensile strength but decreased the shear strength. The intermetallic compounds with cleavage fracture existed at the interface and ductile fracture occurred at other positions.