A refrigeration system and a control method thereof. The refrigeration system includes a compressor and a condenser, and further includes a first throttling device for receiving liquid refrigerant from the condenser; an ejector having a high-pressure fluid inlet, a fluid suction inlet and a fluid outlet, the high-pressure fluid inlet of the ejector is connected to the first throttling device, the fluid outlet of the ejector is connected to a flash tank, a gas-phase outlet of the flash tank is connected to a compressor inlet, a liquid-phase outlet of the flash tank is connected to an evaporator via a second throttling device, and the evaporator is connected to the fluid suction inlet of the ejector; and a controller configured to control an opening of the first throttling device based on a pressure difference between the fluid outlet and the fluid suction inlet of the ejector.