The invention discloses a power grid operation power flow automatic extraction and equivalence method based on CIM/E and QS files. The regional power grid data screening of the QS files essentially realizes regional screening of all element table segments in the QS files. Due to the fact that the full-path names of the elements in the QS file and the matched CIM/E file are consistent, a region mapping table of the elements can be formed by means of the CIM/E file, and then QS file data are screened according to the mapping table. According to the method, element region information in a CIM/E file is utilized, and connection between regions in a termination parent region set and a root node parent region is blocked by customizing the termination parent region set; and stopping searching when an area in the termination parent area set is searched during topology searching, and mapping the element to the level of area to form an element-termination parent area mapping relationship meetingthe screening requirement, thereby realizing automatic extraction of the power grid data of the target area based on the QS file.