Compression ratio adjusting structure of screw compressor and screw compressor

The utility model provides a compression ratio adjusting structure of a screw compressor and the screw compressor, and belongs to the technical field of compressor equipment. The shaft neck sealing structure comprises an oil cylinder body, an air suction end seat and an adjusting assembly. A guide rod hole, an air suction cavity and a slide valve guide hole which are communicated in sequence are formed in the air suction end seat. The adjusting assembly comprises an adjusting piston, a guide rod, a sliding valve and an adjusting cushion block, the guide rod is arranged in the guide rod hole, the air suction cavity and the sliding valve guide hole in a penetrating mode, the adjusting piston is arranged in the oil cylinder body in a sliding mode and fixedly connected with one end of the guide rod, the sliding valve is arranged in the sliding valve guide hole in a sliding mode and fixedly connected with the other end of the guide rod, and an exhaust port is formed in the sliding valve. The adjusting cushion bloc