The invention discloses a movable lock arm rotating locking mechanism and a using method thereof. The movable lock arm rotating locking mechanism comprises a shell, an upper support plate, a lower support plate and an unlocking mechanism, wherein the shell comprises an upper shell body and a lower shell body; the upper support plate is fixed in the upper shell body; the lower support plate is fixed in the lower shell body; a limiting groove is formed in the lower shell body, a square protrusion is arranged at the center of the upper support plate, and a square pit is formed in the center of the lower support plate; the upper support plate and the lower support plate are connected through a rotating arm, and the unlocking mechanism is arranged on the side, away from the rotating arm, of thelower support plate and is wrapped with the lower shell body; and the unlocking mechanism comprises a switch key, a transmission arm, a transmission shaft and transmission lock arms. the transmissionarm is connected with the switch key and the transmission shaft, the transmission shaft is fixed in the limiting groove of the lower shell body, and the two ends of the transmission shaft are provided with the vertical transmission lock arms. According to the movable lock arm rotating locking mechanism, the problems that a common locking mechanism is complex in unlocking process and bad in locking effect, and internal articles cannot be protected are solved.