A fan assembly includes a first fan and a second fan stacked together. Each of the first fan and the second fan includes a frame and a supporting base received in the frame. Several extending portions extend from a bottom of the frame of the first fan. A buckling block is formed on an inner side face of each of the extending portions. Several receiving portions are formed at a top of the frame of the second fan corresponding to the extending portions, respectively. A positioning groove is defined in each of the receiving portions. The buckling blocks are engagingly received in the positioning grooves.