The invention discloses a high-mobility transistor and a preparation method thereof, and belongs to the field of a functional electronic device. A high-mobility double-layer or three-layer graphene film is utilized as an electronic transport channel, and conductivity property thereof is modulated by stress and doping characteristics; when voltage is added to a gate end, the current in the channel is adjusted, thereby realizing function of an HEMT device; since the double-layer or three-layer graphene film conductivity chances with doping, an N-type HEMT and a P-type HEMT can be prepared on the same GaN simultaneously; and the N-type HEMT and the P-type HEMT form a phase inverter of a digital logic circuit, thereby realizing radio frequency and microwave frequency band digital logical operation function.