Developing technologies to store hydrogen efficiently, safely, and economically is essential to achieve the application of hydrogen, among which V-based body-centered cubic (BCC) alloys are a promising material with a high theoretical storage capacity, but, the high cost of V hinder their practical applications. In this work, a novel V alloy with only 5 at% V was developed by suction casting (SC) method, reaching a dehydriding capacity up to 2.9 wt% H. The microstructural control and de-/hydrogenation mechanism for the developed alloys were further investigated systemically. It showed that the low-V alloy prepared by traditional casting displayed Laves phase, and the practical capacity only reached 2 wt% H. Instead, when the suction casting was used in preparation, the developed alloy maintained the single BCC phase and yielded 3.6 wt% H practical capacity, already comparable with V-based alloys. In addition, for the low V SC alloy, after hydriding, the phase structure was transformed from BCC to face-center cubic (FCC), easy to be recovered back to the original BCC structure. The hydrogenation kinetic is controlled by the nucleation growth mechanism with low activation energy, and the enthalpy change △H, was further confirmed by the differential scanning calorimetry curves. This work provided a significant guide for designing a new-generation hydrogen storage alloys with low cost and excellent hydrogen storage performances.