The real-time monitoring of rotor life comsumption makes urgent demands on exact real-time calculation of the thermal rate in analyzing thermal stresses.In order to eliminate the data fluctuation in temperature sampling and meet the demands of real-time calculation

the zone linear regression is adapted to accomplish the data filtering of thermal rate curves instead nonlinear regression

and the time subdomains are so divided

that the later one covers as much as possible the data of former one except first sampling data.As a result

a recurrence formula of the regression has been worked out.The exactness of the formula has been verified by numerical simulation.The convergence and filtering efficiency of the method are very well.