A fixing means for a heat dissipater is provided to position the heat dissipater and a heat-generating element, which includes a heat-dissipating base and a positioning frame. The surface of the heat-dissipating base is provided with a plurality of heat-dissipating pieces. The center of the plurality of heat-dissipating pieces is provided with a sliding groove. Further, the positioning frame is formed into a T-lettered shape and constituted of a transverse rod and a pressing end. The pressing end is accommodated in the sliding groove of the base to abut against the surface of the base. Both side faces of the transverse rod are provided with a screw hole, respectively, for receiving a locking element. With the downward force generated by the connection of the locking element, the pressing end of the positioning frame can be caused to abut against the surface of the base, thereby to efficiently press the gravity center of the base and fix the position of the heat dissipater with respect to the heat-generating element.