By using Glauber model,the number of nucleon-nucleon collisions in heavy-ion collisions was discussed,based on which,after considering the effect of energy loss of nucleons in collisions,the pseudorapidity distribution against impact parameter for multiplicity in final state in nucleus-nucleus collisions was presented,and by employing it,the experimental measurement carried out by BRAHMS Collaboration in Au+Au collisions atsNN=200 GeV was analyzed.The results are in good agreement with experimental observat...