Abstract: Based on investigated and collected data of Beijing Hi-tech industry,the authors applied organizational proliferation and density-dependent selection which was put forward by scholars Hannan and Carroll to the evolvement law of Hi-tech industry population.Research indicates that enterprise population of Beijing Hitech industry is undergoing a process of organizational proliferation,and at the same time,there are competitions.By comparing the regression results of two models,the evolvement of Hi-tech industry population is in the later stage of growth and earlier stage of mature,and it also shows that enterprise population of Beijing Hi-tech Development Zone needs further gathering.