3D multi-slab acquisition is an important technique for high-resolution isotropic diffusion imaging. To further accelerate the acquisition, simultaneous multi-slice (SMS) excitation can be combined with multi-slab. Although either multi-slab or SMS acquisition can be described using a 3D k-space, it’s hard to describe simultaneous multi-slab (SMSlab) using a 3D k-space. In this study, it’s shown that by using RF modulation and gradient encoding together, SMSlab acquisition can also be described by a 3D k-space. It’s further demonstrated that parallel imaging techniques, such as 2D SENSE and 2D GRAPPA, can be used to recover the under-sampled k-space from SMSlab.