A fan module includes a fan (10), a bracket (20), and a locking member (30). The fan includes a pair of parallel side walls (12) each defining through holes (122) therein. The bracket includes a pair of parallel side plates (26) for securing the fan therebetween. The side plates are perpendicular to the side walls of the fan. A locking hole (262) is defined in one of the side plates. The locking member is sandwiched between the fan and one of the side plates of the bracket, and has a resilient arm (322) and two pairs of resilient posts (326) inserting between the side walls of the fan. A protrusion (3262) is formed on each post and removably engages in the corresponding through holes of each side wall of the fan. A locking tab (3222) protrudes from the resilient arm and detachably engages in the locking hole of the bracket.