The invention discloses an SCATS coil data-based traffic state online quantitative evaluation and prediction method, which relates to the traffic state online quantitative evaluation and prediction method in the technical field of traffic. The SCATS coil data-based traffic state online quantitative evaluation and prediction method comprises the following steps: acquiring traffic parameters and uploading the traffic parameters to a traffic information centre by an SCATS coil; performing quality evaluation and control on actually-measured data by a computer; performing traffic parameter virtualtime sequence construction on the actually-measured data subjected to the quality evaluation and control; performing the quality evaluation and control on virtual time sequence data; performing traffic congestion automatic identification on the virtual time sequence data of the parameters; performing short multi-stage prediction on the virtual time sequence data of the traffic parameters; and on the basis of the short multi-stage prediction on the virtual time sequence time of the traffic parameters, performing traffic congestion spreading range prediction and duration prediction and issuing prediction results to a traffic administrative department to provide more forcible basis for decision making for the traffic administrative department.