The invention discloses an automobile vibration response-based method for identifying road unevenness information on line. The method comprises the following steps: Step I, calculating a first time domain generalized International Roughness Index (IRIE1) and a second time domain generalized IRIE2 which correspond to two different vehicle speeds u1 and u2 on a calibration road, measuring an automobile vibration response value of a calibration vehicle at a vehicle speed u, and respectively building a first regression model of the IRIE1 and the automobile vibration response value and a second regression model of the IRIE2 and the automobile vibration response value; Step II, measuring an automobile vibration response value of the calibration vehicle at the vehicle speed u on a road to be measured; Step III, respectively substituting the automobile vibration response values into the first regression model and the second regression model, and calculating a first time domain generalized IRIE1' and a second time domain generalized IRIE2' of the road to be measured; Step IV, calculating a road frequency index and a road unevenness coefficient according to the IRIE1' and the IRIE2'. The method provided by the invention can identify the frequency index and the road unevenness coefficient on line at the same time.