A novel approach to exfoliating graphite into graphene using ultrasound coupled with a shear mixer in supercritical CO2 is presented in this article. The influence of the ultrasound power and the shearing speed on the exfoliation efficiency was systematically studied, and the optimal processing parameters were achieved. In comparison with either the ultrasound or the shearing method, the coupling approach obtained a higher yield, up to 82.6%, and about 60% of the graphene sheets had fewer than three layers. The electrical conductivity of the film formed by the obtained graphene was up to 1.18 x 10(6) S/m. A synergy exfoliation mechanism was proposed: the ultrasound activated the edges of the graphite, generating the gap between the graphite layers, and the shear mixer peeled off the graphene layer from the gap simultaneously. The coupling approach of ultrasound and the shear mixer enabled the production of the graphene.