The present invention provides a Flash device and a preparation method thereof. Through preparing a metal silicide in the control gate of a Nor Flash, compared with a traditional Nor Flash device, the control gate resistance is effectively reduced, the erasing/writing efficiency of the programming ability of a unit area is improved, and the cycle characteristic of the unit area and RC delay are improved. At the same time, the Flash device and the preparation method are also suitable for 55nm and below process, the further reduction of a critical dimension is facilitated, and the Flash device with small dimension and good performance is prepared.