Many recent researches in telecommunication area take lots of attentions to long range depen-dence（LRD） in traffic . In this paper

we study the impact of LPD on queuing performance from a lot of simula-tion experiments which are designed carefully . We draw some conclusions different with those in former papers

and analyze the reasons why those papers gave that kind of doubtful ideas. our results indicate that the correla-tion characteristic of traffic is very important

and the short range dependence is a more dominant characteristicthan LBD.