In order to obtain the judging threshold of the driving fatigue objectively and accurately,the driver's eye movement data,reaction time and execution time under the sober and mental fatigue states are collected from a driving simulator.The driver's eye movement data,reaction time and execution time during continuous driving are used to respectively describe the driver's gaze characteristics,reaction ability and executive ability.Then,a rela- tionship model is constructed by adopting the entropy weight method to obtain the weighted average of the three kinds of data.In the model,the three kinds of data and the quantitative values of the driving fatigue are respec- tively taken as the independent and dependent variables.In order to improve the objectivity of the driving fatigue threshold,the variable threshold determination method is adopted to select the thresholds of the optimal fatigue at the first fatigue threshold and the secondary fatigue threshold.Moreover,the change rules of the driver fatigue un- der the continuous driving condition are revealed,and the quantitative method of the driving fatigue is evaluated.Experimental results show that the proposed method can effectively improve the precision of the driving fatigue quantization,and it has a broad application prospect in the driving safety field based on the prevention of driving fatigue.