Uncertainties accompany practical system inherently complicate the stability analysis for the weak-grid-connected voltage source converter (VSC) under DC-link voltage control (DVC). In this paper, structured singular value (SSV, also called μ)-based approach is proposed to explore the stability region of this (multi-input-multi-output) MIMO system considering parametric uncertainties. First, system small-signal model is established, and the generalized uncertain model is formulated using linear fractional transformation (LFT) algorithm. Then, system stability boundary is determined by the comparison between the value of μ and the criterion, under multiple parametric perturbations. Finally, eigenvalues analysis and time-domain simulation results validate the predictions accuracy of the proposed μ approach.