The present disclosure provides a filament power supply for an electron accelerator and an electron accelerator. The filament power supply includes: a rectifier circuit configured to convert a power frequency AC voltage signal into a DC voltage signal; an inverter circuit configured to convert the DC voltage signal into an AC voltage signal; a sampling circuit configured to sample the AC voltage signal to obtain a current sampling signal or a voltage sampling signal; a pulse width modulation control chip configured to adjust a pulse width modulation signal until a voltage of the current sampling signal is equal to that of a reference current signal, or a voltage of the voltage sampling signal is equal to that of a reference voltage signal; a modulation circuit configured to modulate the power frequency AC voltage signal to obtain a modulation signal and output the pulse width modulation signal and the modulation signal.