Low alloy steel SA508 autogenously welded with Type 309L/308L austenitic stainless steel cladding is one of the common forms of the dissimilar metal weld joint (DMWJ) in the primary water of a pressurized water reactor (PWR). Accurate evaluation of the inhomogeneous mechanical propriety and crack growth driving force at the corresponding place on the DMWJ is important for integrity analyses of a PWR. In this study, the mechanical propriety of the DMWJ was obtained using a combined Vickers hardness test and the stress-hardness relationship. And, a finite element (FE) model for the DMWJ in a PWR with continuous transition mechanical propriety was built using a predefined temperature field method. Based on consideration of the heterogeneity mechanical properties on the DMWJ with the continuous transition mechanical propriety, the Mises stress distribution and J integral on the crack tip with different crack lengths was analyzed using elastoplastic FE analysis. As shown by the distribution profile of the Mises stress distribution and J integral on the crack tip, the inhomogeneous mechanical propriety distribution is found to significantly affect the crack driving force when the crack tip is close to the fusion boundary.