A refrigerating and freezing device and a control method therefor. The method comprises: starting an air extracting pump (40), enabling the air extracting pump (40) to run for a first preset time and then stopping the air extracting pump (40), so that the concentration of nitrogen in an air-regulating fresh-keeping space reaches a preset concentration threshold; detecting whether the air-regulating fresh-keeping space is opened and then closed; and if yes, after the stop duration of the air-regulating fresh-keeping space exceeds a second preset time, controlling the air extracting pump (40) to be started, and enabling the air extracting pump (40) to continually run for the first preset time and then stopping the air extracting pump (40).