In this paper a united Gauss-Pearson-IV (UGP) distribution model is presented by definition of a weight factor R, which represents the percent rate between the number of channeling ions and the number of all ions implanted for the first time based on determination of some basic relation ships and correction of some basic conclusions of Pearson-IV distribution model. The UGP models fit the experimental results of high energies B ions implantation into crystal Si with and without oxide mask and low energy BF2 implantation into crystal and amorphous Si very well. (C) 2008 Elsevier B.V. All rights reserved.