The invention discloses a free falling body winch brake device applied to a dynamic compactor. The free falling body winch brake device comprises a free falling body dynamic compactor winch and a brake, wherein inner brake sheets, outer brake sheets, a bearing I, a bearing II, an elastic check ring I, an elastic check ring II of the brake are in bilateral arrangement; a transmission shaft is radially supported by the bearing I and the bearing II, and the elastic check ring I is clamped in a clamping groove of a support base; a spline housing is connected to the transmission shaft through an inner spline; the elastic check ring II is clamped in the clamping groove of the transmission shaft; the inner brake sheets are connected to the spline housing through the inner spline; the outer brake sheets are connected to the outer ring of the brake through an outer spline; a piston is mounted in the inner cavity of the outer ring of the brake; a big spring is mounted in a piston hole, a middle spring is mounted in the inner hole of the big spring, and a small spring is mounted in the inner hole of the middle spring; the outer ring of the brake is connected to the support base through a bolt I. The free falling body winch brake device applied to the dynamic compactor solves a series of problems caused by oversize diameter of the brake sheets; as three groups of combined springs are adopted by the brake, the whole structure is more compact.