The invention relates to an ultra-thin device for parking and taking cars through full floating mechanical hands. Two sides of a longitudinal movement trolley are symmetrically provided with full floating mechanical hands, and the ultra-thin device consists of the longitudinal movement trolley and the full floating mechanical hands symmetrically arranged on the two sides, wherein the longitudinal movement trolley comprises an underframe, a running mechanism driving motor, a driving wheel, a driving wheel driving shaft, and a driving wheel driving gear; the full floating mechanical hand comprises a mechanical arm driving mechanism, a mechanical hand transition sliding plate, a mechanical arm, linear guide rails arranged on the inner and outer sides of a long beam on the underframe of the trolley respectively, and a swinging arm guide groove, wherein the mechanical hand transition sliding plate drives the mechanical arm to move. The device is ultra-thin, and two sets of independent full floating mechanical hands float freely in a set range, can be placed on a conveying trolley to form a horizontal movement type mechanical parking device, and can be placed on a stacker to form a laneway stacker type mechanical parking device without a carrying plate and a comb teeth rack; and the interbedded clear height is only 1.65 meters so that the construction investment is reduced, the structure is simple, the maintenance is convenient, and particularly the device is applicable to large mechanical garage.