The invention discloses a reusable launch vehicle landing buffer device including at least three sets of buffer mechanisms. The at least three sets of buffer mechanisms are evenly distributed around the tail end of a launch vehicle body in the circumferential direction and connected to the launch vehicle body; and each buffer mechanism includes N compressing and releasing mechanisms, a main pillarunfolding joint, an auxiliary unfolding device, a shell unfolding joint, a retractable main pillar, a shell and a buffer, wherein the top end of the retractable main pillar is connected with the launch vehicle body through the main pillar unfolding joint, the bottom end of the retractable main pillar is fixedly connected to one end of the buffer through a flange, the other end of the buffer is hinged to the head of the shell, the tail of the shell is connected to the launch vehicle body through the shell unfolding joint, one end of the auxiliary unfolding device is connected to the launch vehicle body, the other end of the auxiliary unfolding device points to the outer side of the launch vehicle body at a certain angle, and the N compressing and releasing mechanisms are evenly distributedon the outer side of the launch vehicle body. The reusable launch vehicle landing buffer device solves the problems of the small buffer capacity, the poor landing stability, the slow deployment speedand the like of an existing landing buffer device.