Based on the theory of two-dimensional（2D）

orthogonal polynomials

the function of dynamic load is fitted by using the primary functions sequence.The identification of the distributed dynamic load can be transformed into the solution of the fitting coefficients.For the finite element model of the rotating elastic beam

the unknown distributed force is identified by the load identification theory of the continuous beam in time domain.Numerical simulation shows that the method has high precision as long as enough data information of feedback points are collected.It is simple and effective for engineering applications.