Method for estimating rotating speed of engine

The invention provides a method for estimating the rotating speed of an engine, which comprises the following steps of: S1, in a current code operation cycle, acquiring a coarse value of the change rate of the rotating speed according to a difference and a time difference between two collected actual measured values of the rotating speed of the engine which are closest to each other; and S2, according to the correction coefficient of the rotation speed change rate, correcting the rough value of the rotation speed change rate from the current moment to the moment when the actual measurement value of the engine rotation speed is collected next time, and obtaining the correction value of the rotation speed change rate. And S3, according to the actual measured value of the rotating speed of the engine and the corrected value of the rotating speed change rate which are collected closest to the current moment, the current rotating speed estimated value of the engine is estimated. According to the method, the engine