The present invention relates to a CLC and operation method thereof equipped with a loop seal separator using magnetic oxygen carrier particles and a magnetic separator. And more particularly, the present invention relates to a loop seal separator using magnetic oxygen carrier particles and a magnetic separator, wherein the loop seal separator comprises a duct into which the ash and magnetic oxygen carrier particles, discharged from a reducer, flow; a magnetic separator to separate the ash from the magnetic oxygen carrier particles, flowing into the duct, by magnetic material; an ash discharge pipe to discharge the ash, separated by the magnetic separator; and an oxygen-carrier-particle discharge pipe to encourage the magnetic oxygen carrier particles, separated by the magnetic separator, to flow into an oxidizer.