[Show abstract][Hide abstract] ABSTRACT: Based on the basic concepts and analysis methods of power supply capability, the paper analyzed the increase of distribution network efficiency in parallel operation. Firstly, the analysis process and formulas of the power supply capacity in parallel operation under general connection mode was given. And then the hand-in-hand connection mode was adopted as the specific network connection mode. The increased range of the power supply capability was obtained in parallel operation compared to split operation under different settings of main transformers in stations, different connection modes in stations and different network connection degrees. Finally, the conclusion that the power supply capability can be improved significantly in parallel operation without full network connection was obtained.