A rural domestic sewage dosage self-adjusting disinfection device is characterized by comprising an electrolysis mechanism, a water inlet mechanism, a disinfection mechanism, a controller and an external power supply. The electrolysis mechanism further comprises a cathode reactor used for containing a sodium chloride solution, an anode reactor used for containing the sodium chloride solution, a sodium chloride storage device, a first siphon, a cathode electrode, an anode electrode and a conductivity detector, and on the premise that water flow passes through, a first electric conductor and a second electric conductor are conducted. The invention further discloses a disinfection method of the rural domestic sewage. When the device is used, sewage inlet does not need to meet uniform and continuous conditions, the treatment effect of the device is not affected even if the device is re-started after being used for several days, and the device is wide in adaptability to external conditions.