The invention discloses an analysis method for a running state of primary equipment at an interval of a substation. In-station intervals are classified and analyzed according to a series structure interval, a general interval, a bus interval and a main transformer interval; a set of interval state calculation table is formed according to various running states and a reasonable state of the primaryequipment at the interval and comprises interval state values, numbers and results; with regard to the bus interval and the main transformer interval, the running state is determined according to a live-line condition; the general interval under a wiring mode such as single-bus connection and dual-bus connection is substituted into the first interval state calculation table, and the running stateof the primary equipment at the interval is obtained by combining a load power; and the string structure interval under three second wiring mode is substituted into the first interval state calculation table, and the running state of each interval is obtained by calculation. By the analysis method, the running state of each interval in the station is more intuitively and accurately mastered by operating staff, and normal running of the substation is guaranteed.