The design concept of “modularization and skid-mounted package” for large natural gas purification plan has not only put forward higher request for construction period, but also presents a huge challenge for electrical design. The purpose of this study is to accumulate valuable experience in the design of natural gas purification plant. This paper analyses actual data of the power load on current situation in the 2^nd Moxi natural gas purification plant and proposes the selection of load factor on electrical load calculation in view of the fact that the power load is lower than the common level. In addition, the characteristics, problem and solution of electrical skid-mounted design in process plant area are proposed in this paper. Three-dimension design PDMS is one of the highlights in this project. In connection with the power load distribution and general layout, this paper presents a design version with cable interlayer in power substation and analyses the advantages and downside of this design proposal. The summary and discussion of electrical design on large natural gas purification plant, which is helpful for the selection of transformer capacity and the reduction of investments and operating cost in the future, can provide the basis for electrical optimization of large natural gas station. Meanwhile, the experience in the design of electrical skid-mounted and cable interlayer in power substation is accumulated by this paper.