A window blind includes a headrail, a covering assembly including a plurality of slats and a bottom rail, a lifting mechanism including a driving module and a lift cord assembly operably connected to the driving module, a tilt mechanism adapted to drive the slats to rotate, and an auxiliary unit provided between the tilt mechanism and the lifting mechanism. The lift cord assembly is connected to the bottom rail for expanding or folding the covering assembly. The covering assembly is in a first state when each and every one of the slats is substantially parallel to each other and correspondingly rotatable by the tilt mechanism, and is in a second state otherwise. When the covering assembly is in the second state, the auxiliary unit is drivable by the tilt mechanism to make the lifting mechanism further release the lift cord assembly, changing the covering assembly into the first state again.