The present study deals on the geometry effects of the spherical pressure vessel(SPV) and the crack configuration on the variation of the stress intensity factor (SIF) through the crack line. The pressurized vessel is subjected to the pressure and thermal gradient (thermo-mechanical loading). The 3D analysis of defected thick-walled pressurized sphere vessel is done using the numerical Finite Element Method (FEM). This work covers a wide range of the crack configurations in vessels with different geometries. The effect of the various parameters such as thermal gradient, RO/Ri, a/c and a/t on the variation of the dominant first mode of SIF through the crack front is studied. The obtained SIF’s are compared with the mechanical loading results (in the absence of the thermal gradient). The results show that parameters such as the aspect ratio of the crack, the ratio of the crack depth, the pressure vessel wall thickness and also the temperature gradient have significant effects on the distribution of the SIF through the crack line. It can be seen that the thermo-mechanical condition is more critical.