A helmet is disclosed including: a helmet body; a jaw guard with two fork handles through which the jaw guard is mounted on the helmet body and rotatable around a fixed axis relative to the helmet body; a shield assembly including a shield and a bracket, which is movable between a lowered position and a raised position relative to the helmet body; and a lifting mechanism including a trigger located beside the bracket of the shield assembly and driven by the fork handles of the jaw guard, and the trigger can touch the bracket of the shield assembly at the lowered position and raise the shield assembly from the lowered position. The lifting mechanism further includes an elastic element with one end connected with the bracket, which is arranged to make the shield assembly continue to move to the raised position after the shield assembly leaves the lowered position.