The invention discloses a protection method of a 110kV sectionalized single-bus configuration integrated protection device, which integrates the logic of 110kV bus differential protection, 110kV sparepower automatic switching and 110kV sectionalized protection, optimizes configuration schemes such as the hardware, terminal block, analog quantity, switching value and fixed value list of the integrated protection device, realizes the functions of 110kV bus differential protection, 110kV spare power automatic switching and 110kV sectionalized protection, expands a loop closing and opening operation application program and gives full play to the functions of 110kV bus differential protection, 110kV sectionalized protection and 110kV spare power automatic switching of the integrated protectiondevice, thereby being especially applicable to intelligent substations, and being also applicable to conventional substations. The protection method can also be applied to the 110kV side of a 220Kv substation adopting sectionalized single-bus configuration or double-bus configuration.