The utility model discloses a light catalytic cracking separator, including light catalytic cracker, knockout drum, heat exchanger and water sealed tank, still including the airtight feeding storehouse, screw extrusion feeder, a nitrogen purging valve, the feeding control valve that connect gradually, it observes sight glass, bottom solid ejection of compact observation sight glass, pyrolysis furnace bulk temperature meter and solid reactant blow -down valve to be equipped with the top on light catalytic cracker, at light catalytic cracker to being equipped with thermometer, pipeline sight glass and first pressure gauge between the knockout drum, be equipped with bottom flowing back valve bottom the knockout drum, be equipped with low level flowing back valve on the heat exchanger, be equipped with first emptying valve, the second temperature meter and third pressure gauge between heat exchanger to water sealed tank, be equipped with second emptying valve, water seal and feed liquor valve on the water sealed tank, be provided with the 2nd nitrogen purging valve, check valve, flowmeter, control valve and sample valve on the pipeline between nitrogen supply (NS) device and water sealed tank. The utility model discloses can effectively separate organic matter in the rubbish and inorganic matter.