The present study was undertaken to invesitigate the protozoan fauna of Three Qorges Area at yangtze River. Samples were collected at the area from Fengjie to Yichang in 1987-1988. 234 species of Protozoa consisting of 29 species of Pigmentless Phytomastigophora and zoomastigophora, 61 species of Sarcodina and 144 species of Ciliopnora, and including one new species (Difflugia caudata sp. nov.) and two new subspecies (Difflugia urceolata eurystomus ssp. nov. and Conchophthirus lamellidens medionucleus ssp. nov.) have been identified. Among them, 46 species are new record in China. A detailed description of new species and new record species are given in the dissertation. To compare with the protozoan fauna of Tibet, some lakes in the middle and lower portions of rangtz River and Suoxiyu Natural Protection Area, most species of Protozoa could be found sin all the areas. It seems no significant geographical difference; Considering the cosmopolitan distribution of the majority species of Protozoa, the analysis of geographical distribution of Protozoa is based on the Predominant species as evidenced by the relative abundance and the frequency of occurrence. In sarcodina and ciliata the first dominant species are Centropyxis aculeata aculeata and Cinetochilum margaritacenm respectively. the condition reflects the feature of subtropical zone. And these species are considered faunal elements of the Oriental realm. More studies must be carried out to learn exactly about the geographical distribution of Protozoa. The influence of some ecological factors on the distribution of Protozoa has been discussed. The cause of Phenomena of more protozoan species in YiChang area was analysed. Due to the constriction of Gezhou Dam across the river, The current velocity slowed down a great deal. Therefore the water quality is suit for the growth of Protozoa. In order to adapt the rapid flow water in Three Gorges Area, many species of Protozoa were found in attached filifoun algae, since the localites are more stagnant waters, rich in decomposing organic substances.