The utility model provides an inlet pressure control device of a refrigeration compressor of a propane refrigeration system. The device comprises a gas-phase return pipeline, a first-stage pressure reducing valve, a first-stage pressure reducing valve rear pressure gauge, a second-stage pressure reducing valve and a second-stage pressure reducing valve pressure gauge, wherein the gas-phase returnpipeline is connected between a high-pressure gas-phase pipeline and a low-pressure gas-phase pipeline of the propane refrigerating system; wherein the first-stage pressure reducing valve, the first-stage pressure reducing valve rear pressure gauge, the second-stage pressure reducing valve and the second-stage pressure reducing valve pressure gauge are sequentially connected to the gas-phase return pipeline, and the inlet pressure of a propane refrigeration system compressor is automatically adjusted by the first-stage pressure reducing valve and the second-stage pressure reducing valve through the gas-phase return pipeline. According to the device, negative pressure operation of the system in the refrigerating process is avoided, overpressure and freezing blockage of the refrigerating system are avoided, and safe production of the natural gas purification device is guaranteed.