The invention discloses an oxygen control device and method for a lead-based coolant reactor and a reactor system. The oxygen control device comprises an oxygen concentration detector, a thermocouple,a first storage tank, a first pipeline, a first valve, a second storage tank, a heater, a second pipeline, a second valve and a controller; and the controller is used for controlling the first valveand the second valve according to a received oxygen concentration signal sent by the oxygen concentration detector and a lead-based coolant temperature signal detected by the thermocouple, and adjusting the oxygen concentration of a lead-based coolant in a main reactor container. According to the oxygen control device and method for the lead-based coolant reactor and the reactor system, oxygen concentration control is conducted though a solid phase oxygen control technology and a gas phase oxygen control technology simultaneously; the gas phase oxygen control technology is used for decreasingthe oxygen concentration in the lead-based coolant, a project is easy to achieve, and meanwhile the lead-based coolant can be purified; the solid phase oxygen control technology is used for increasingthe oxygen concentration in the lead-based coolant, the response speed is high, and additional oxide impurities are not generated; and through simultaneous use of the two technologies, good points are adopted, and shortcomings are avoided.