In Northwest China, igneous rocks are widely developed within the Permian strata. Their high velocities and rapid lateral variations degrade the imaging of the underlying strata, producing structural distortions and weakened reflections that can be misinterpreted as faults or low-relief structures. Moreover, conventional model building struggles to recover their velocity field. To address this challenge, we present a two-step velocity-model-building workflow that combines offset vector tile (OVT) domain reflection tomography with full-waveform inversion (FWI) to characterize the Permian igneous rocks. In the first step, after five-dimensional data regularization and OVT sorting, full-azimuth OVT-domain reflection tomography was used to build the velocity model, constraining lateral velocity variations in the igneous interval that conventional offset-domain tomography leaves unconstrained. This yields an initial model accurate enough for the subsequent inversion. In the second step, FWI with an edge-preserving total-variation regularization was applied. The regularization retains the blocky boundaries of the igneous body in place of structure-oriented smoothing, and the inversion successfully characterizes the velocity structure of the Permian igneous rocks. The effectiveness of the inversion is demonstrated by comparisons of common-image-point gathers, well velocities, and pre-stack depth migration images. The workflow provides a practicable route to velocity modeling and imaging in land igneous-rock settings.