The invention discloses a double-compression-ratio engine. The engine comprises a high compression cylinder, a low compression cylinder, a high compression
cylinder air inlet mechanism, a low compression
cylinder air inlet mechanism, an exhaust mechanism and a
crank connecting rod
power output shaft. Each air inlet mechanism comprises an
electronic throttle valve, a valve set, and a valve transmission set. The engine is provided with two different cylinder acting operation
modes at the same time, and during idling,
constant speed and deceleration, more acting power is assigned to the high compression cylinder, so that the efficiency is improved, during acceleration, augmentation, and high speed, more power is assigned to the low compression cylinder, so that the power response speed is increased, and the efficiency and the output of acting of the cylinders are correspondingly improved. The double-compression-ratio engine is more suitable for requirements of automobiles on environmentalprotection and power under various working conditions.