The invention discloses a power grid fault self-healing system in a 110kV chain type power supply mode and self-healing logic. The 110kV chain type power supply mode includes two 220kV power supply stations and a plurality of 110kV serial supply stations connected in series between the two 220kV power supply stations, and a line switch at one side of one of the 110kV serial supply stations is located in a split position and is an open loop point. The self-healing system includes a master station device and a plurality of substation devices connected in series, each 220KV power supply station and each 110kV serial supply station are each provided with one substation device, and the master station device is connected with one of the substation devices; and each substation device is provided with an analog quantity acquisition interface, an input quantity acquisition interface and an output quantity output interface which are used for being connected with a power station so as to acquire an analog quantity signal and a switching value signal of the power station and execute a protection control command sent by the master station device. When a power grid fault occurs, the system provided by the invention can rapidly isolate the fault and start a standby power supply to supply power, thereby realizing a power grid self-healing function in a chain type power supply mode, and improving power supply quality.