A fan module is detachably mounted in a chassis. The chassis includes a sidewall defining a locking slot. The fan module includes a bracket including a base plate defining a first through slot, a fan fixed to the base plate, a fan duct fixed to the base plate beside the fan, and a locking member. The fan duct includes a side plate defining a second through slot. The locking member is fixed to the fan duct. The locking member includes a locking portion extending through the second through slot of the fan duct and the first through slot of the bracket to lock into the locking slot of the chassis.