This application discloses a voltage monitoring method, a voltage monitoring apparatus, and an electric vehicle. The voltage monitoring apparatus includes a power conversion module and a microcontroller electrically connected to the power conversion module. The power conversion module is configured to output a voltage. The microcontroller includes an ADC module, a monitoring module, and an IO module. The ADC module is configured to obtain an output voltage of the power conversion module, and determine whether the output voltage encounters an exception. The monitoring module is configured to: when the output voltage encounters an exception, output a control signal through the IO module. The power conversion module correspondingly stops outputting a voltage based on the control signal. Based on this, diagnostic coverage of the power conversion module can reach 99% for a single-point fault metric, thereby meeting a requirement of a corresponding level of ASIL D.