For the phenomenon that false alarms, leak alarms frequently occur in existing methods for highway warning, a fan warning model for curved roads is proposed based on millimeter wave radar, the establishing method of the model is introduced, the related parameters of the model are determined, the concept of driving safety margin is put forward, a graded early warning mechanism is established based on driving safety margin, the early warning methods and the critical points to enable these methods are given. The simulation results show that the fan warning model for curved roads can effectively reduce false alarms and leak alarms, the model is feasible.