Abstract: With the comprehensive promotion and construction of smart substations, the application of secondary devices in smart substations is becoming more mature, which promotes the further integration of common functions of secondary devices. Developing and constructing new-type power systems have also put forward new requirements and generated new devices for smart substations. It is necessary to explore the new integration scheme of secondary devices in combination with the development trend of smart substations and the new need for new-type power systems. The status of the integration scheme of secondary devices in smart substations is summarized. The integration of merging unit and intelligent terminal in the process layer, which is promoted from 110kV to 220kV and above voltage level, is discussed, and the impact of relay protection based on SV(sample value) and GOOSE(generic object-oriented substation event) common port transmission and multiple-sampling rate of SV is analyzed. The wide-frequency measurement device, new fault recording device, cluster measurement and control device, bay-group control unit, and vertical integration scheme in the bay layer are presented as the integration of the data communication gateway and phasor data concentrator and the integration of wide-frequency processing unit and phasor data concentrator in station layer are described. Based on practical engineering applications, the feasibility of each scheme and the maintenance are discussed, and the integration scheme is analyzed in conjunction with the issue of domestic chips. This can provide a reference for developing and constructing of smart substations in the context of developing new-type power systems.