Abstract: An online monitoring method of driver state and a system using the same are provided. First a driver model is established, wherein the driver model generates a steering angle to control transportation means for riding according to the lateral position error of the riding transportation means. Next, a system identification processing is performed on the lateral position error and the steering angle of the riding transportation means to obtain a transfer function of the driver model. After that, an analysis processing is performed on the driver model transfer function to extract specific information therefrom, following by performing an assessment processing on the specific information and multiple statistics of raw data to generate the driver state assessment.