The invention relates to a four-stroke gasoline engine, in particular to a decompressed gas-intake internal combustion engine with high compression ratio, belonging to an engine. The decompressed gas-intake internal combustion engine with high compression ratio comprises an oil spout system, a spark plug, an gas cylinder, a piston, a piston pin, a connecting bar, a crank, an oil bottom shell, an intake pipe, an intake valve, an exhaust valve, an exhaust pipe and a crank case and also comprises a gas-intake decompressed valve, a valve drive of the gas-intake decompressed valve, an air pressure sensor and a flow sensor which are all arranged on the upper part of a motion valve and an extract opening of the crank case along a gas-intake direction to be used for restricting gas-intake quantity; the decompressed gas-intake internal combustion engine is improved in compression ratio and can not generate abnormal combustion such as deflagration, surface ignition, and the like. In addition, the decompressed gas-intake internal combustion engine with high compression ratio saves a water cooling system for a prior internal combustion engine. The invention reduces the exhaust emission, saves the energy, and also simplifies the structure of an internal combustion engine, decreases the part number and lowers the production cost on the basis of enhancing the heat efficiency of the internal combustion engine.