The role of fossil diatom study in paleollmnology is to analogize the ancient lakes9 reconstruct their lake envirmnental evolution histories and find out lake function and lake variation regularities based upon the distribution, ecology and environmental condition of living diatom flora in modern lakes, and upon some other organic and inorganic indicators and dating data as well.Diatom has become an important tool in paleolimnologicai studies due to its high abandance, well-preserved frustule, sensitivity to changing environments, wide distribution and uncomplicated identification.Initial researche,on paieoenvironments of lacustrine fossil diatoms began at the middle nineteenth century.The subject has being forged rapidly since the 1980s, including 7 major aspects as follows: (1) systematic classification of diatoms, (2) relationship between diatoms and environmental factors, (3) diatoms and lake acidification and eutrophication, (4) diatoms and climatic changes, (5) transfer function between diatoms and water chemistry, (6) influence of reworking and dissolution on diatom distribution, and (7) correlation of diatoms and sedimentary pigments.Fossil diatom studies began rather late in China.There accumulated some research data in the past twenty years, including mainly: (1)fossil diatoms in Tertiary diatomaceous earth deposits, (2) fossil diatoms in plateau lakes in Xizang (Tibet), and (3) Quaternary lacustrine fossil diatoms and environmental changes, guice the academic level is quite lower as compared with the modern international levels The Chinese paleontological and Quaternary geological fields have to strengthen the studies on lacustrine fossil diatoms and their environmental significance.