The material and grain boundary properties of dissimilar weld joints in nuclear power plant are quite different with homogenous material. The narrow zone near fusion boundary (FB) has been found to have the highest residual strain and hardness, which makes dissimilar weld joints more susceptible to stress corrosion cracking (SCC). Limited experimental conditions, varied influence factors and diverging experimental data make it difficult to accurately predict the SCC behavior of dissimilar weld joints. To clarify the effect of sampling location on SCC driving force such as for cracking in an Alloy 182-low alloy steel dissimilar weld joint, a more reasonable material model with inhomogeneous mechanical property, performed by finite element codes, is applied to simulate the complex mechanical properties of material around FB line. When growing crack enters into the high hardness zone (HHZ) near FB line, the crack driving force decreases quickly. The HHZ is expected to be a serious barrier to further SCC crack growth into low alloy steel (LAS). Potential path for crack growing is also discussed.