Abstract: ICE ON/OFF control strategy is critical for fuel economy in the hybrid electric vehicle (HEV). The fuel cumsumption cut off at ICE is at OFF state when the vehicle stops especially at vehicle jams. It significantly profits for more fuel saving. Motor-only drive mode is rarely used in real-time control because of the power system meet the uncertain driver demand. Battery state of charge (SOC) balance also affects ICE ON/OFF control decision. ICE ON/OFF state optimization is still a critical problem that is rarely effectively resolved. Minimum Principle was used in real-time control and has a global optimization in many papers. However, there is no paper to apply this algorithm in ICE ON/OFF control optimization. This paper introduces a novel control method using Minimum Principle to select an appropriate ICE state, which extracts rules from the optimal results applied to real-time control based on predicted route information. Experiments prove proposed route-based control significantly improves the fuel economy. Compare to the conventional control strategy, route- based control has 18.0% fuel cut, very close to DP-based control.