In order to understand the influence of the flat curve angle value on the driver"s physiological load on the plateau highway, select the National Highway 314 line in the interval of 3000m～4030m as the test section, and select the heart rate growth rate and pulse blood volume (BVP) as the driver"s physiology. The evaluation index of change, and the heart rate growth rate and pulse blood volume distribution coefficient are programmed by MATLAB, and the K value is obtained as the evaluation index of the driver"s physiological load. Through the comparative analysis of the measured data, the heart rate growth rate, BVP and K value are quantitatively analyzed. The flat curve corner is worth changing and a regression model is established. The results show that there is a strong correlation between the heart rate growth rate, the BVP value and the K value and the flat curve rotation angle, and the K value decreases with the increase of the flat curve rotation angle value, especially in the range of the rotation angle value of 0°-7°. Under the dual influence of altitude and corner value, as the corner value is smaller, the higher the altitude, the larger the K value, the higher the driver"s physiological load, and the higher the traffic safety risk.