Abstract: In order to directly measure and accurately obtain the oil saturation of cores, processes such as graphene gel impregnation, aging and supercritical drying were used in conjunction with a conventional sponge to obtain the graphene sponge material with an adjustable pore diameter. At room temperature, crude oil absorption of graphene sponge material is as high as 80.5 times its own mass, and the graphene modified sponge coring tool is designed and developed. The grapheme modified sponge coring tool adopts pre-filled sponge protection fluid and a sealed piston to protect the sponge material from being polluted. Through indoor laboratory experiments, the diameter of sponge liner is determined to be 0.6–1.0 mm less than that of the core, and a strip sheet is used to press and protect the sponge liner while satisfying the requirement of oil absorption and core feeding. Based on the comparison with conventional methods, the measurement and calculation methods of the oil saturation of cores are determined. This new sponge coring tool can effectively collect the crude oil escaping from the core without compromising the core recovery. Therefore, it demonstrates a high potential for application.