The optimal SNR efficiency of 3D multi-slab multi-shot DWI acquisition can be enabled by using a TR range of 1-2s. However, due to the low feasible slab thickness, the multi-slab acquisition can only achieve limited brain coverage when using a short TR. In this study, we first develop a 3D multi-band (MB) iDW-EPI sequence with MB-EVI-based navigator to increase brain coverage when using optimal TR. Second, we extend 3D-MUSER algorithm, which is proposed in another study, to reconstruct 3D-MB-iDW-EPI data with 3D phase correction. Our preliminary result demonstrates the feasibility of 3D MB DWI with 3D phase correction.