Abstract: Bottom backscattered echoes of 41 sites located in the north of Yellow Sea and Bohai Sea were acquired by a vertically oriented echosounder working at 20 kHz.Based on a time domain incoherent intensity model of seafloor high frequency backscattering,the sediment classification with inversion of seafloor sediment geoacoustic parameters is investigated.By maximum likelihood matching between the averaged echo envelope and the model output with a global simulated annealing-downhill simplex optimization(SIMPSA),the sediment mean grain size is estimated.It is found that the fluctuation of the echo and the variance of the estimated parameters are effectively reduced once the echo envelope is normalized by the total echo energy before calculating the averaged envelope.And the estimated parameters are consistent with the ground truth.Simultaneously,the percentage of totally correct classification is 75.6%.