The invention provides a flexible gear shifting device for transmission through flexibility and rigidity joint. The flexible gear shifting device comprises a clutch shell, a friction piece, a tooth-shaped gasket, a large piston, a duplex gear, a plunger ring, an oil spraying shaft sleeve, a small piston, a cylindrical spiral compression spring, a disc-shaped spring and a four-oil-way shaft; and ahydraulic system is used for controlling axial movement of the large and small pistons to realize conversion from friction force transfer of the torque to spline transfer. The invention provides the gear shifting device for transferring the power through combining flexibility with rigidity; under the condition of low torque, synchronization of a clutch and a gear is realized by dint of the friction force of the friction piece; and under the condition of high torque, the power is transferred through a spline.