Based on the coupling method of computational fluid dynamics (CFD) with discrete element method (DEM), numerical investigation on the gas-solid hydrodynamics and erosion characteristics is conducted in a 3-D pressurized fluidized bed with immersed tube bundles. The effects of operating pressure on time-averaged solid-phase characteristics, solid circulation features, granular temperature and tube erosion patterns are analyzed. Elevated pressure accelerates both upward and downward particle flows, resulting in a lower solid concentration in the bottom part compared to the upper part. A theory is proposed to explain the occurrence of large solid velocity fluctuation. The distinct erosion distribution of each tube is found to be strongly related to solid flux distribution. The mechanism of bubble-induced tube erosion is represented and validated by simulation result. (C) 2016 Elsevier Ltd. All rights reserved.