Abstract: Monitoring and analyzing the fatigue and attention state by using the machine vision is one of hotspots in the assistant safe driving system.Calculating driver face orientation angle is the precondition of analyzing attention state of drivers.The idea of face and face organ location is introduced firstly and the techniques for driver face orientation in this system are discussed mostly.Based on analyzing the rotary motion of the head，an algorithm for calculating the facial rotary angle of drivers is proposed.Practice proves that the algorithm proposes acts in real time and obtains excellent effect，which lays a good foundation for further information-collecting and analyzing of the driver’s attention state.