With the increasing use of VSC-HVDC links, voltage stability control has become a vital issue in AC/DC power systems. This paper proposes an optimal coordinated control (OCC) method in AC/DC systems incorporating VSC-HVDC to exploit the ability of VSC-HVDC to enhance steady-state voltage stability. First, this paper extends L-index to AC/DC systems incorporating VSC-HVDC. Then based on this, two kinds of optimal coordinated control are proposed respectively for voltage deviation correction and voltage stability enhancement. The optimal coordinated control is modelled as a linearly constrained quadratic programming problem based on sensitivity, which can get a solution quickly. The model considers characteristics of different controllable variables so it can coordinate the controllable resources of a power system. Furthermore, based on the proposed optimal coordinated control, a control strategy is designed which can jointly ensure voltage stability margin and maintain voltage magnitude in a reasonable range. In this way, the ability of VSC-HVDC systems participating in voltage stability control is fully exploited. The result of the simulation on modified New England 39-bus power system shows that the proposed method can comprehensively coordinate control variables and effectively enhance voltage stability.