The invention relates to a device and a method for performing cryogenic separation and purification on carbon monoxide and hydrogen. According to the device and the method, raw material synthetic gas enters a synthetic gas purification unit for gas impurity removal; the impurity-removed gas is cooled by a first plate-fin type heat exchanger, enters an evaporator in a rectifying tower to be cooled, and then enters a gas liquid separator through a second plate-fin type heat exchanger; hydrogen-enriched gas at the upper part of the gas liquid separator after separation is performed by the gas liquid separator is reheated by the heat exchangers through pipelines and then enters a hydrogen collecting unit; liquid at the lower part of the gas liquid separator enters the rectifying tower through a pipeline and a throttling valve to participate rectification; the rectified liquid carbon monoxide is reheated by the heat exchangers through pipelines, enters a carbon monoxide compressor and then is conveyed into a carbon monoxide collecting unit; and the rectified gas carbon monoxide is reheated by the heat exchangers through pipelines and then is conveyed into a carbon monoxide collecting unit. According to the method for performing cryogenic separation and purification on the carbon monoxide and the hydrogen, disclosed by the invention, the cold of the heat exchangers is provided by gas reheat generated by separation, and nitrogen circulating refrigeration is not needed, so that energy consumption is reduced.