The pressure field of bonding region in explosive welding has been measured with a manganin pressure gauge. In the experiment，the welding configuration of unsymmetrical collision of aluminium-aluminium plates is adopted. The gauge is buried at different depthes，the flyers of two thicknesses are used. The explosive is a mixed one consisted of PETN and foam rubber (density-0.9g/cm3，measured mean detonation velocity-3000m/s).