The invention discloses a frequency and voltage modulation device and method for a poultry electric stunning device. The frequency and voltage modulation device comprises a three-phase voltage isolation transducing unit (1), a three-phase bridge-type rectifying circuit (2), a DC / DC double-path direct-current power outputting module (3), a voltage modulation controlling unit (4), a PLC (Programmable Logical Controller) functional module (5), an upper computer controlling system (6), a frequency modulation controlling unit (7), a direct-current pulse outputting module (8), a liquid crystal display unit (9) and a direct-current pulse output controlling unit (10). According to the technical scheme of the invention, a novel frequency and voltage modulation technical scheme is provided; as high-frequency and low-voltage direct-current pulse electric output is adopted, the speed of electric stunning is high, and requirements of a slaughter assembly line are satisfied; meanwhile, wing breaking and extravasated blood of poultry caused by nervous flapping can be reduced, bleeding is facilitated, and the sanitation safety of meat products and the reliability of the production quality are ensured.