To tackle the problem of crack failure caused by thermal-induced stress of elastomeric materials in electronic packaging, research has been carried out around the characterization of bulk moduli of elastomer materials and thermal-induced stress modeling method. The bulk moduli of five silicone gels with different hardness, namely GNJ-1~GNJ-5, was quantitatively obtained by a passive-confining pressure device. Test results showed that bulk moduli of these silicone gels were relatively close, which were 1068.4 MPa, 972.0 MPa, 1067.5 MPa, 1092.0 MPa, and 1140.4 MPa, respectively. The Poisson's ratios of these silicone gels were obtained based on the relationship with bulk modulus and Young's modulus, the value of which were between 0.49975 and 0.49997. An incompressible constitutive model was built based on the measured material properties, and the thermal-induced stress simulation model was validated through designed tests. The results showed that the simulation model agreed well with the test data and the error was between 17.6% and 23.6%.