The types and working principle of startup system for oncethrough boilers and bypass system for steam turbines have been expounded. The simulation of cold and hot starting process for once through boilers with recircuilating pump has been carried out by using the developed computer programme OTBSP. providing basis for design and operation of startup system for oncethrough boilers. A mathematic model for computing combustion rate based on pressureraising curve and on opening degree of the highpressure bypass regulating valve during the starting process of unit has also been correctly established by using the said programme

providing basis for designing the bypass system of steam turbines and for optimizing the startup curve.