Abstract: Numerical simulations suggest that plateau/ridge subduction and back-arc spreading would influence magmatism and island-arc crustal growth subduction-zone. In this paper, we take the Izu-Bonin-Mariana (IBM) subduction zone paper as a case to test the above observation. Moho depth variations are estimated based on Inversed gravity anomaly by satellite altimetry and density modelling for different layers, and the trend of the Moho inversion result can well match the seismic interpretations. Crustal thickness variations are mapped based on gravity-inversed Moho, open-source topography and bathymetry as well as sediment thickness. The island-arc crustal volume variations along strike indicate that (1) the subduction of the Ogasawara Plateau and the Dutton Ridge necked and thickened the arc crust, and they also increased the arc crust volume, (2) the opening of the Marian Trough reduced substantially the island-arc crustal growth.