An embodiment of the invention discloses a non-self-regulating plant control method and device. The non-self-regulating plant comprises an operating variable and a manipulated variable. The nonself-regulating plant method includes establishing a steady-state gain matrix of the nonself-regulating plant; according to the steady-state gain matrix, determining the rate relationship of the operating variable and the manipulated variable; according to the rate relationship, regulating the operating variable in real time to ensure that, at the premise of minimal variation of the operating variable, the manipulated variable reaches a preset target range or target value after a preset first control time. Compared with the prior art, the non-self-regulating plant control method and device has the advantages that control contraction of steady state and dynamic state is omitted, and the non-self-regulating plant is efficiently controlled based on the marginal stability feature of the non-self-regulating plant.