Abstract: To obtain the characteristics of the free-field pressure with underwater explosion, the time-frequency characteristics of the monitored free-field pressure signals are studied through wavelet analysis, based on the experimental free-field pressure data subjected to underwater explosion.By using these signals, the pressure-time curves and the energy distributions in different blasting frequency bands are obtained.The result shows that the obtained time-frequency characteristics of free-field pressure can be used to generate the shock wave signal, the after flow signal, and the second pressure pulse, and by analyzing the energy and frequency component, it is easy to get the detailed time-frequency information of the free-field pressure signal intensity, frequency and duration.More than 90% of the energy of the shock wave pressure signals condenses in the band lower than 8 kHz, and the highest level of energy appears below the frequency of 4 kHz, and special attention should be directed to the low frequency band below 250 Hz of the after flow signal as well as the second pressure pulse for ship structure and equipment.Overall, this paper provides reference for shock-resistance analysis of the ship structure.