A typical digital substation， Tangshan Guojiatun 220 kV Project， is introduced. The main technical features and implementation scheme of the project are analyzed， including the function of protection， measurement and control integrated into 220 kV transmission line and transformer protection relays， distributed disturbance data recording， the program sequence control in digital substation， simplify the secondary circuit， the no-electrical protection for transformer implemented based on generic object oriented substation event（GOOSE）， the distribute installment of the process level devices on the switchyard.