Coaxial rigid rotor high-speed helicopter hovers and climbs by two rotors with coaxial reversal， and flies forward at high speed by tail propulsion propeller. The rotor does not need to tilte， so it has higher reliability than tilt rotor aircraft and has good development prospect. The coaxial reverse drive system is the key moving part of the coaxial rigid rotor high-speed helicopter. The configuration principle of coaxial transmission system is analyzed， and the contrarotating drive system is classified into four types for the requirements of contrarotating output function： cylindrical gear， bevel gear， face gear and differential gear system. The development status at home and abroad， main characteristics and application of the four types of contrarotating drive system configurations are discussed， which provides the basis for the selection and design of the drive system configurations of the coaxial helicopter with different requirements.