The invention discloses a horizontal supercritical fluid autoclave and an apparatus thereof, and the autoclave including an autoclave body, an end cover, a material frame, a wedge block and a wedge block driving device, wherein the autoclave body is horizontally arranged, and the wedge block driving device can drive the wedge block to move in the radial direction, so that the wedge block can be clamped into a clamping groove at the inner wall of the open end of the autoclave body to lock the end cover or can be separated from the clamping groove of the autoclave body to open the cover. The end cover is small in size and light in weight, and the wedge block type cover mechanism with quick unlocking and locking is adopted; and the structure is simple, the opening/closing of the end cover is simpler and more convenient, and the installation space is saved.