A smooth switch access scheme of the process level equipment is proposed, which is applied in the intelligent reconstruction of the traditional substation. The study is carried in various views such as the system structure, the communication network solution, the functional configuration, and the interactive companion mode of the data. Based on the system hardware design, the signal data flow analysis is also showed. In order to meet the demand of signal access of large quantity and the integrated acquisition and control, the hardware is designed for SV and GOOSE sending and receiving, and based on this hardware system structure, a multi-bus framework is set up including LVDS bus, IO bus, GPS bus, and the management bus. The scheme realizes large quantity data access and control, meanwhile meets the demand of smooth switch access during the substation intelligent reconstruction.