Strong frequency-varying signal always undergoes a rapid frequency change within a short time duration. Converting its 1-D waveform into the 2-D time-frequency (TF) plane is convenient for us to understand the structure of the strong frequency-varying signal. Time-reassigned multisynchrosqueezing transform (TMSST) is a recently proposed time-frequency analysis (TFA) method, which owns the capability to provide an energy concentrated time-frequency representation (TFR) result for the strong frequency-varying signal. However, the fixed-point iterative estimation manner of the group delay in the TMSST method would lead to some non-reassigned TF points and further affect the readability of the TFR result. To address this issue, a post-processing method for the TMSST is proposed in this study. In the proposed method, the group delay of the strong frequency-varying signal is estimated by local maximizing the TFR result provided by TMSST in the time direction, and then the TF coefficients from the TMSST are rearranged among the time direction on the basis of the new estimated group delay. Results from simulation and experimental case studies verify that the proposed method can provide a more energy-concentrated TFR result in comparison with the other existing TFA methods.