Characteristics of the altimetry waveform are studied to improve the accuracy of sea surface height measurement. Based on the existing methods, the leading-edge-detection-based multi-leading edge and multi-threshold waveform retracking method is presented. Then, the method is applied to the waveform processing over the China offshore to enhance the precision and resolution of altimetry. As a validation, the gravity anomaly data are computed from the retracked data and compared with the ship-born gravity. Results show the method can improve the altimetry precision greatly.