Armrest capable of hiding and expanding seat space

The utility model relates to an armrest capable of hiding and expanding seat space, which consists of an armrest, a movable bracket and a base, and comprises a main body structure and an adjusting system, a main body structure comprises a handrail plate, an upper rotating hinge, a movable support, a lower rotating hinge and a base. The adjusting system comprises an adjusting button, a sliding block, a sliding way, a positioner, a guide rod, a positioner counter-force spring, a pull wire, a fixed pulley, an adjusting wire, a steering pulley and a button spring. A slide way is arranged in the armrest plate, a guide rod is arranged in the slide way and connected with a slider in a matched mode, positioners are arranged on the two sides of the slider, the slider is matched with the positioners, the outer sides of the positioners are connected with positioner counter-force springs, the bottom of the slider is connected with the upper end of a movable support through an upper rotating hinge, and the lower end of th