This paper presents a Multi-step Matched Field Inversion (MS-MFI) approach, which makes use of the varying sensitivities of wave-fields at various frequencies to reduce the inversion problem into a sequence of smaller inversions with fewer unknowns to estimate at each stage. Different parameters are estimated using data at different frequencies according to their sensitivities. Geoacoustic inversion are carried out using explosive charge data from the ASIAEX East China Sea Experiment and MS-MFI. Inversion results are discussed and compared with core data.