The invention provides an architecture of an inner bridge connection type intelligent substation process layer, comprising an incoming line information collection control device, an inner bridge connection information collection control device, and a main transformer high-backup protection device. The incoming line information collection control device is used for collecting the current information on each incoming line interval and transmitting the current information to the main transformer high-backup protection device. The inner bridge connection information collection control device is used for collecting the current information on each inner bridge connection line interval and transmitting the current information to the main transformer high-backup protection device. A main transformer body information collection control device is used for collecting the current information of the neutral point of a main transformer and transmitting the current information to the main transformer high-backup protection device. The main transformer high-backup protection device makes judgment on the basis of the current of the incoming line, the current of the inner bridge connection line and the current of the neutral point of the main transformer. Therefore, even if a main transformer differential protection device is out of service or is being maintained, grid equipment can still operate safely under the protection of the main transformer high-backup protection device.