The application discloses a high voltage interlock circuit and a detection method thereof. The circuit comprises: a first switching module; a second switching module, comprising a first driving unit and a first switching unit arranged in isolation, the first switching unit is arranged between a second power supply and a second power ground; a third switching module, comprising a second driving unit and a second switching unit arranged in isolation; a fourth switching module, arranged between the fourth power supply and the first power ground; a controller. The embodiments of the application improve the accuracy of fault detection.