An active canister purge system may include: a canister trapping a fuel vapor generated in a fuel tank; a purge control valve allowing the trapped fuel vapor to be purged from the canister into an intake pipe; a purge pump forcefully pumping the fuel vapor trapped in the canister into the intake pipe; a pressure sensor detecting a pressure at an inlet of the purge control valve; and a controller determining whether the pressure at the inlet of the purge control valve is varied on the basis of a pressure variation in the intake pipe in a non-purging condition to diagnose an open stuck state of the purge control valve.