Dissimilar joint between 2219-T87 and 2219-T852 alloys were produced by VPTIG. The weakened zone of the joint was determined by tensile test, and the weakening mechanism and fracture behavior of joints were discussed after observing of the grain size, element segregation and precipitates distribution. The results showed that the average ultimate tensile strength and elongation of VPTIG joints at -196℃reached up to 314 MPa and 5.68%, respectively. All joints were broken from the heat affected zone of 2219-T852 side, where showed the worst segregation of the Cu element, dissolving and coarsening of precipitates, non-uniform grain sizes, and the strain localization caused by the joint deformation. The fracture originated at the edge of the weld seam from the joint bottom surface, and propagated along the heat affected zone to the top surface, showed a mixed fracture mode.