The invention discloses an electric generator iron loss test apparatus and an experimental method. According to the invention, one end of a grouping test cable is connected directly with a switchgear, the other end is wounded onto an iron core of an electric generator for a set number of turns and then connected to the switchgear, and the switchgear is connected with a power supply through a power supply cable; the grouping test cable comprises a plurality of groups of test cables of different number and length. The invention has the beneficial effects of being capable of greatly accelerating the test connection link, ensuring a safe and reliable test, meanwhile greatly reducing work hours and improving work efficiency.