Abstract: This paper applies the differential eguation for Hu Hai-Chang's middle-thick plates and its boundary conditions,putting forward four types of try function:1.Beam-function 2.Levy-function 3.Hyperbolic and triangular series 4.Elastic foundation membrane function.Part of the above functions strictly satisfy boundary conditions in terms of boundary integration approach of Least Square.The calculations show that the methods raised in the paper are of high precision and practicubility.