The estimation of equivalent and depth of underwater explosions is an important task of the hydroacoustic monitoring in the International Monitoring System(IMS) of the Comprehensive Nuclear-Test-Ban Treaty(CTBT).In order to effectively estimate the equivalent and depth of underwater explosion in near and far-fields,the relationship between the ratio of the first and second periods of the bubble pulsation and the bubble radius and depth was fully used based on the semi empirical formula of bubble pulsation period.The analysis results of near-field underwater explosion show that the average estimated equivalent and depth are about 118 g and 7.96 m,76 g and 21.4 m,1.23 kg and 44 m for different actual TNT equivalent values and blasting depths of 100 g and 7 m,100 g and 25 m,1 kg and 50 m,respectively.These results show that the depth estimation is more accurate than the equivalent estimation.Furthermore,the proposed method failed for a small explosion equivalent of 100 g and a depth of 50 m,which indicates that the method is limited in explosion depth.Finally,this method was used to analyze the far-field underwater explosions recorded by IMS hydroacoustic stations,and the equivalent and depth estimation results were consistent with the references,which indicated that this method is also suitable for the far-field explosion estimation.