A power supply having detachable fan includes a power supply main body and a fan module. The power supply main body includes a shell. Walls of the shell define at least one compartment, and the walls have at least one fastening portion. The fan module includes a case, a fan and a handle. The case has an outlet and an inlet. The case is movably disposed in the compartment, and the inlet faces an interior of the shell. The fan is disposed in between the outlet and the inlet. The handle is pivotally connected to two sides of the outlet of the case, and two ends of the handle respectively have a mating portion. The mating portion and the fastening portion of the immediately adjacent wall of the shell are engaged.