The invention discloses a power supply protection device and a power supply protection method. The power supply protection device comprises a driving circuit, a logic control unit and a protection module, wherein the driving circuit is used for adjusting an external voltage to output a driving voltage according to a first driving signal and a second driving signal, the logic control unit is used for generating the first driving signal and the second driving signal according to a protection signal and a pulse wave signal, the protection module is used for sequentially outputting a plurality of test currents to test a plurality of impedances of the driving circuit before the external voltage is received by the driving circuit, generating a plurality of voltage signals according to the plurality of impedances and comparing the plurality of voltage signals with a plurality of reference voltages to generate the protection signal. Therefore, by the power supply protection device according to the invention, various impedances of various driving circuits can be detected before an applied system is started so as to determine whether an abnormal situation occurs in an internal component or not, and power supply protection is achieved on other components in the system.