Abstract: An industrial park is supplied by the 110kV Nanshan Substation. With the growth of power load, the Jiang'an Substation was newly built. After the Jiang'an Substation was put into operation, the operation mode of the original substation was adjusted to enhance power supply reliability, which required the analysis and calculation of the substation’s protection settings. This paper analyzes the protection configuration of the 110kV power systems of the two substations, and studies the coordination relationship of the corresponding protections in light of their operation modes. It is found that the actual operation mode of Nanshan Substation is inconsistent with the designed one, leading to the problem of protection override tripping in the event of a bus fault. Corresponding solutions are put forward accordingly.