Abstract: This paper is based on investigations of the vertical dist ribution of fleas and their host s in nine sample areas in seven mountain ranges and refers to related data analyzed with statistical methods. According to the standardized mean of the diversity index for fleas in the vertical zones of each mountain range , the paper analyses and discusses the problems of the relationship of host s and of important environmental factors with the geographical dist ribution t rends and rules of flea species diversity in Yunnan Province’s Hengduan Mountains. The result s show geographical dist ribution t rends such that flea species diversity gradually decreases f rom the northwest to the south and the northeast . This t rend is related primarily with humidity and rainfall , then secondarily with latitude , flea richness , geographical environmental condition , vertical zonation , human activities , etc. It is concluded that the different geographical dist ribution t rends between fleas and host s was the main cause of their different adaptability to the environment , of which humidity is one of the important factors. In addition , the flea species richness in the Hengduan Mountains is the highest in the Chinese flea fauna. It was demonst rated that habitat heterogeneity in the Hengduan Mountains affect s species diversity , which act s on the relationship between species and area.

Key words: thermal cyanophytes, species diversity, Yunnan Province