The invention relates to a power station exhaust check valve and a pneumatic control method thereof. The exhaust check valve is applied to pipelines of non-corrosive media, such as steam and water, in power station or thermal station exhaust systems or other systems in order to protect operational safety of a steam turbine. There are no professional valve manufacturers who manufacture exhaust check valves in China before; with development of Chinese power industry, the demands for the exhaust check valves are wider; only annual import of exhaust check valves is up to 6000000 USD; the defect of high cost is confronted with. The method includes: mounting a bonnet (2) above a valve body (1), mounting a cylinder (3) and a pin (4) inside the valve body, connecting the pin to a rocker (5), connecting the rocker to a valve clack (6), and welding a layer of stainless steel or hard alloy on the surface of the valve body by surfacing. The pin is further connected with a lengthened bar (7), and a shift fork (8) and a gravity hammer are mounted on the lengthened bar. The power station exhaust check valve and the pneumatic control method are applied to controlling flow of pipeline media.