The invention provides an ejector throttling refrigeration system and a drainage method. The ejector throttling refrigeration system comprises a throttling device, wherein an outlet of the throttling device is connected with a first inlet of an ejector, and the throttling device is used for converting a liquid-state refrigerant at the front end of the first inlet of the ejector into a gas-liquid mixing refrigerant, and when the ejector throttling refrigeration system works, the gas-liquid mixing refrigerant is ejected through the ejector to form the gas-liquid mixing refrigerant in the atomizing state. Through the technical scheme, the throttling device is arranged at the front end of the ejector in the ejector throttling refrigeration system, and therefore a refrigerant flowing out of a condenser is subject to pressure drop through the throttling device, and therefore the refrigerant is converted into the gas-liquid mixing refrigerant, the gas-liquid mixing refrigerant is ejected to the atomized refrigerant through the ejector, and therefore the drainage effect of the ejector on the gas-state refrigerant flowing out of the evaporator is improved