Abstract: There are always closed orbit distortions and closed orbit shifts produced by various error sources. They are detrimental to beam performance and must be corrected by closed orbit correction and orbit feedback system. Singular value decomposition(SVD) method is currently being used in the closed orbit correction and feedback system in Hefei light source. In this article, the mathematical algorithms for orbit correction and feedback are introduced, especially constrained linear least squares method(CLLS). Compared with SVD method, CLLS method pays more attention to sensitive position. Running results using this method are given, and they show that the orbit reproducibility and beam orbit stability of special sensitive beamline is improved significantly.