The invention belongs to the technical field of engines, and particularly discloses an engine
cylinder block structure and an operation method thereof, an engine and a vehicle, the engine
cylinder block structure comprises a first cylinder and a second cylinder, a first
piston is slidably connected in the first cylinder in the axial direction, and a second
piston is slidably connected in the second cylinder in the axial direction; the driving
assembly is used for driving the first
piston and the second piston to slide; the first cylinder is provided with a sealable first air inlet hole and a sealable first air outlet hole, the second cylinder is provided with a sealable second air inlet hole and a sealable second air outlet hole, and the device further comprises a communicating
assembly used for communicating the first air outlet hole with the second air inlet hole; the volume of the first cylinder is larger than that of the second cylinder. By the adoption of the scheme, the advantages of a two-
stroke engine and a four-
stroke engine can be integrated, the
variable compression ratio is achieved, the homogeneous compression ignition acting mode of the engine is achieved, and the heat efficiency and acting efficiency of the engine are improved.