The invention discloses a pressurization 
air filter for a four-cylinder four-
stroke generator. The pressurization 
air filter comprises a main pipeline. The two ends of the main pipeline communicate with the outside world and an air inlet end of an engine correspondingly. An 
air pump is fixed to the middle of the main pipeline. The side, close to the engine, of the main pipeline is divided into a first 
air purification cavity and a second 
air purification cavity. The other end of the main pipeline is divided into a first air inlet cavity and a second air inlet cavity. The first air purificationcavity, the second 
air purification cavity, the first air inlet cavity and the second air inlet cavity are each internally provided with a valve. The pressurization 
air filter has the advantages thatthe 
air pump pumps air from the air inlet cavities to the outside world and injects air into the air purification cavities, at the same moment, an air inlet door of only one cylinder of the engine isopened, while the air pumping quantity of the 
air pump is larger than the air suction quantity of the single cylinder, thus pressurization can be generated on the engine, the effect that sufficient 
oxygen can enter the cylinder of the engine is ensured, sufficient burning of 
fuel oil is facilitated, and the purposes that 
power performance of the engine is improved, specific power is improved, fuel economy is improved, and 
exhaust emission and 
noise are reduced are achieved.