A switch power converter and method of testing and adjusting is provided. A switch power unit comprises at least a power switch for transform of the power. A controller is configured to generate a control signal for the power switch. A detector is configured to detect an output voltage signal and/or an output current signal of the switch power unit and output a sampling signal. A testing and adjusting unit is configured to receive the sampling signal and output a testing signal to the controller. The testing and adjusting unit comprises a compensator. The compensator attends the testing and adjusting of the switch power converter. An AC disturbing signal various in frequency causes the difference in the sampling signal and the testing signal so as to test open-loop transfer function of the switch power converter, the compensator compensates frequency response characteristic of the switch power converter, when the frequency response characteristic of the switch power converter doesn't match a target frequency response characteristic.