Abstract: This paper focuses on the analysis of voltage regulation of large users in Shanghai under the new circumstance of Doing Business. Through the comparison of current regulation rules of power supply voltage for large users in other foreign and domestic cities, the primary optimal strategy to promote Doing Business has been raised. Focused on the users with the capacity from 8MVA to 40MVA, the sensitivity analysis with the adjustment of capacity limit has been fully studied. Taking the limit capacity for 10kV users as a typical case, the influence of increasing the upper limit have been considered from the utility, users and the whole society perspectives. Along with the technical-economical evaluation, the paper finally proposes a practical optimal strategy of users voltage regulation, to advance a mutually beneficial and win-win situation of entire society.