By minimizing the probability of instability,an optimization approach to enhancing static voltage stability of power system under uncertain conditions was proposed on the basis of the static voltage stability region boundary (SVSRB) and its sensitivity to control variables.To obtain the explicit approximations to the SVSRB and the sensitivities,on the basis of the idea of generalized polynomial chaos (gPC),an approach combining stochastic Galerkin method and primal-dual interior point method was introduced.Case study in IEEE 39-bus system verified the validity and accuracy of the proposed optimization approach.