A signal converter equipped with an overvoltage protection mechanism includes a pulse width modulation unit, a timing processing unit, an overvoltage detection unit, a pulse width control unit and a multi-level conversion unit. The pulse width modulation unit converts an analog signal into a pulse signal. The timing processing unit converts the pulse signal into a digital signal and outputs the digital signal to the overvoltage detection unit. When the digital signal is higher than the maximum limitation or less than the minimum limitation, the overvoltage detection unit outputs an over-threshold signal to the pulse width control unit to allow the pulse width modulation unit to perform feedback adjustment and prevent the multilevel conversion unit connected to the timing processing unit from causing burnout of downstream circuits because the multilevel conversion unit outputs maximum power intensity of signal over a long time.