A fan frame includes a blade holder, a pair of ventilation plates, and at least one side plate. The pair of ventilation plates is attached to opposite sides of the blade holder along a first direction and includes a pair of securing blocks. The at least one side plate is attached to the blade holder along a second direction substantially perpendicular to the first direction and located between the pair of ventilation plates. The pair of mounting slots is defined in the at least one side plate and engaged with the pair of securing blocks, thereby securing the pair of ventilation plates and the at least one side plate to the blade holder.