Marinoan snowball Earth, which ended at ~635 Ma, offers us a set of sedimentary and geochemical records for exploring glacial isostatic adjustment (GIA) associated with one of the most severe glaciations in Earth history. An accurate prediction of GIA-based sea level change associated with a snowball Earth deglaciation will help to explore sedimentary records for sea level changes and to place independent constraints on mantle viscosity and on the deglaciation duration. I mainly examine post-deglacial sea level change characterized by a sea level drop and a resumed sea level rise inferred from the sedimentary records in South China. Such a non-monotonic sea level behavior may be a diagnostic GIA-signal for the Marinoan deglaciation. GIA-model with high deep mantle viscosity and rapid deglaciation explains sedimentary-inferred sea level records.