Abstract: In response to the current issues of the Gas insulated metal-enclosed switchgear secondary control circuit, such as the large amount of original signal usage, complex circuit design, difficulty in circuit function modification, and heavy maintenance workload of cable connections, a full-chain digital control technology solution was proposed. The design, manufacture, and test verification of a 252 kV digital control type GIS prototype were completed, achieving complete digitalization of the secondary control circuit from the source to the end. It has the advantages of one-time collection of original signals for multi-circuit reuse, parameterized configuration of circuit functions, and monitorable circuit status. This simplifies the design of the secondary control circuit, reduces the maintenance workload of cable connections, and enhances the flexibility and reliability of the secondary control circuit.