The steam blowing system of thermal power plants is controlled by DCS(distributed control system), of which the control logic is constructed by traditional sequence control module of DCS. However, the traditional control mode has many disadvantages. Therefore, a new serialization code sequence control(SCSC) mode is introduced, which is clear in structure, simple in maintenance and convenient in use. By the application in a 1 000 MW ultra supercritical unit, it is proved that the SCSC mode is suitable for many control objects, and can be used in many fields.