Interpolation solution to a boundary value problem of harmonic field

This article is a improvement on author's early work (Acta Mathematica Scientia, Vol.30 No.2 Ser.A 2010). In this article, there are two new contributions: 1) The restrictive conditions on approximation domain boundary is improved essentially. 2) The Fejér points is extended by perturbed Fejér points with stable order of approximation.