Abstract: Conventional Chirp parametric sub-bottom profiler acquisition systems typically record only envelope signals with positive polarity, resulting in the loss of phase information in raw data. To facilitate the application of conventional processing methods and subsequent geological interpretation, converting envelope data into waveform data becomes a fundamental prerequisite. Therefore, three methods—filtering, derivation, and Hilbert transform—to extract waveform data from envelope-type parametric sub-bottom profiling data were employed, and the outcome were systematically compared against the real case examples from two survey areas. Results indicate that the filtering method could better preserve the lateral continuity of strata in areas where the continuity of reflective events is poor, which benefits the tracking of sedimentary structures and macroscopic interpretation. The derivation method tended to enhance the high-frequency components of the signal, and reveal more clearly the internal structural variations within the strata and detailed information. This method is suitable for fine structural interpretation in the areas with well-developed sediments. The Hilbert transform method was able to remain the signal bandwidth, retain more low-frequency components, and showed high stability, making it more effective in capturing the reflection characteristics in the areas with significant topographic relief or thin sedimentary layers. In addition, the three methods can also be used in combination to improve the reliability and resolution of sub-bottom profiles. This study provided a new route for processing envelope-type geophysical data with a strong support for the fields of marine engineering survey, seabed resource investigation, and paleoenvironment reconstruction.