The invention relates to the field of intelligent substation testing, in particular to a method for deducing a main wiring diagram of field primary equipment through an SCD (Substation Configuration Description) virtual terminal. The method comprises the following steps: deducing a bus unit wiring mode, a main transformer wiring mode and a line wiring mode of each voltage level of an intelligent substation; performing mapping association with a 'six unification' specification and SCD virtual terminal function configuration, and deriving a wiring diagram of field primary equipment of the intelligent substation; demonstrating whether an SCD function configuration file is correct or not; if the SCD function configuration file is correct, outputting a correct primary equipment wiring diagram;and if the SCD function configuration file is not correct, modifying the SCD function configuration file and carrying out derivation verification from the beginning until the SCD function configuration file is correct. According to the invention, the logic association condition of each equipment virtual terminal of the intelligent substation configuration description (SCD) is examined for designing and debugging personnel more visually, and the main wiring diagram of the field primary equipment is reversely deduced by utilizing the virtual terminal function configuration of the SCD file, so that related personnel are promoted to demonstrate the correctness of the SCD configuration, and the SCD configuration can be adjusted and repaired in time if the SCD configuration is incorrect. Therefore, the running reliability of the whole system is improved.