A sleeve installer is provided, including: a threaded rod; an abutting unit, disposed around and movable along the threaded rod, including first and second abutting assemblies, one of the first and second abutting assemblies being configured to be abutted against a barrel portion of a sleeve assembly, the other of the first and second abutting assemblies being configured to be abutted against a tubular member of the sleeve assembly; and a push unit, including first and second push members which are connected to two opposite ends of the threaded rod, at least one of the first and second push members being movably screwed to the threaded rod, the first push member including a head portion and an urging assembly located at a side of the head portion, the urging assembly and the second push member being respectively abutted against two opposite sides of the abutting unit.