The invention provides a power ring test circuit for a non-isolated DC/DC converter and a control method, and belongs to the technical field of power electronic converters. The non-isolated DC/DC converter circuit to be tested is provided with an auxiliary circuit, wherein the auxiliary circuit includes two parts, one part is a wire connecting an output positive electrode and an input positive electrode of the converter circuit and called an auxiliary line; and the other part is a half-bridge circuit formed by connecting an IGBT (Insulated Gate Bipolar Transistor) switch tube and a diode in series. The auxiliary circuit and the tested DC/DC converter are placed under the same heat dissipation condition and form the test circuit together. The power ring test circuit adopts a scheme of a bidirectional DC power supply or stored energy, thereby greatly saving the cost of the experimental device. Meanwhile, the power ring test circuit avoids the energy waste, and can show great cost advantages in converter test projects with a high current level and a high power level.