A carbon dioxide refrigeration system, comprising: a refrigeration loop, which comprises: a compressor, a condenser, a throttling element and an evaporator which are connected by pipelines, wherein a high-pressure side flow passage of the refrigeration loop is formed from the downstream of the compressor to the upstream of the throttling element, and a low-pressure side flow passage of the refrigeration loop is formed from the downstream of the throttling element to the upstream of the compressor; and a pressure relief and recovery loop, which comprises: a gas storage reservoir, for storing gas-phase carbon dioxide; a pressure relief flow passage, connecting the gas storage reservoir and the refrigeration loop and being suitable for discharging the gas-phase carbon dioxide in the refrigeration loop into the gas storage reservoir; and a recovery flow passage, connecting the gas storage reservoir and the refrigeration loop and provided with a driving apparatus, the recovery flow passage being suitable for recovering the gas-phase carbon dioxide in the gas storage reservoir into the refrigeration loop under the drive of the driving apparatus; characterized in that the pressure relief flow passage 2. connects the gas storage reservoir and the high-pressure side flow passage of the refrigeration loop; and the pressure relief flow passage 2. connects the gas storage reservoir and the low-pressure side flow passage of the refrigeration loop. a refrigeration loop, which comprises: a compressor, a condenser, a throttling element and an evaporator which are connected by pipelines, wherein a high-pressure side flow passage of the refrigeration loop is formed from the downstream of the compressor to the upstream of the throttling element, and a low-pressure side flow passage of the refrigeration loop is formed from the downstream of the throttling element to the upstream of the compressor; and a pressure relief and recovery loop, which comprises: a gas storage reservoir, for storing gas-phase carbon dioxide; a pressure relief flow passage, connecting the gas storage reservoir and the refrigeration loop and being suitable for discharging the gas-phase carbon dioxide in the refrigeration loop into the gas storage reservoir; and a recovery flow passage, connecting the gas storage reservoir and the refrigeration loop and provided with a driving apparatus, the recovery flow passage being suitable for recovering the gas-phase carbon dioxide in the gas storage reservoir into the refrigeration loop under the drive of the driving apparatus; characterized in that the pressure relief flow passage 2. connects the gas storage reservoir and the high-pressure side flow passage of the refrigeration loop; and the pressure relief flow passage 2. connects the gas storage reservoir and the low-pressure side flow passage of the refrigeration loop. a gas storage reservoir, for storing gas-phase carbon dioxide; a pressure relief flow passage, connecting the gas storage reservoir and the refrigeration loop and being suitable for discharging the gas-phase carbon dioxide in the refrigeration loop into the gas storage reservoir; and a recovery flow passage, connecting the gas storage reservoir and the refrigeration loop and provided with a driving apparatus, the recovery flow passage being suitable for recovering the gas-phase carbon dioxide in the gas storage reservoir into the refrigeration loop under the drive of the driving apparatus; characterized in that the pressure relief flow passage 2. connects the gas storage reservoir and the high-pressure side flow passage of the refrigeration loop; and the pressure relief flow passage 2. connects the gas storage reservoir and the low-pressure side flow passage of the refrigeration loop.