The conventional fast algorithm of the steam turbine governing stage's characteristic curve neglects the secondary factor and simplifies the calculation formula

but large relative error still exists.To solve this problem

the calculation formula of the steam flow deflection angle of the nozzle and the velocity coefficient of the moving blade were introduced to improve the calculation method of governing stage characteristic curve.Moreover

by taking a 200 MW unit steam turbine as an example

the calculation algorithm this paper proposed was employed to establish the mathematical model for calculating the governing stage characteristic curve.The calculation was carried out under the design conditions

and the results were compared with that of the conventional calculation method.The results indicate this improved algorithm has higher precision.