A fixture for fixing a data storage unit is disclosed. The fixture includes: a body receives the computer components and defines a protrusion and a hole thereon; a separating piece includes a separating portion correspondingly to the protrusion; a fixing piece includes a lockpin correspondingly to the hole of the body, and the separating piece is set between the fixing piece and the body; and a controlling component fixes the fixing piece on the body. The fixture of the present invention can rapidly fix or remove a data storage unit inside a computer case without any screws. The assembly cost and the maintaining cost of the fixture are low, and the assembly and the disassembly of which is simple and timesaving.