Abstract: The seabed acoustic parameters such as sound velocity, density and attenuation coefficient are important in sound field forecasting and target positioning. The in-situ measurements and seafloor sampling are usually very difficult to implement in the deep ocean, and so, new methods obtaining seabed acoustic parameters need to be found. In the shadow zone of deep ocean, as the range increases, the direct wave will gradually disappear, and the reflected wave and multiple reflected waves play an important role in the sound field. In this paper, the multiple arrival structure of acoustic waves in the shadow zone is analyzed, and the seabed reflection loss varying with grazing angle is obtained by multiple comparisons, which can be used to perform geoacoustic inversion. Finally, the seabed reflection losses obtained by bringing the inversion of seabed acoustic parameters into the acoustic field model are compared with the measured ones, and both results are basically consistent. The analyses of scatter plot and marginal probability distribution in the inversion process represent the credibility of the inversion results. This method provides a feasible solution to the inversion of the seabed acoustic parameters in the shadow zone of deep ocean.