The invention discloses a rapid regulation valve and a rapid regulation method for improving the regulation capacity of a thermal power generation unit. The rapid regulation valve comprises a valve body, a valve seat, a floating disc and a spring; a regulation valve cavity is formed by the valve body and the valve seat in a closed way, the floating disc is arranged in the regulation valve cavity, the floating disc divides the regulation valve cavity into an upper cavity and a lower cavity, and the spring is arranged between the floating disc and the valve body; a control oil port is arranged on the valve body and connected with an electric hydraulic converter, an oil return port is arranged on the valve seat and connected with a check valve, a load pressure oil port is arranged on the floating disc, and the load pressure oil port is connected with a hydraulic servo motor. The invention further provides the rapid regulation method for improving the regulation capacity of the thermal power generation unit. Based on an electric hydraulic control system of a turbine of the novel rapid regulation valve, the rapid regulation capacity of the turbo generator set is effectively improved.