Abstract: The stromatolites are formed by microbial activities of blue-green algae, bacteria,eucaryotic algae and fungi. They are regarded as pare-fossils containing sedimentologic,palaeoecologic, and environmental informations.Two Quatemary stromatolite reefs, dated to be about 130 000 aB.P. and 93 000aB.P.with the ESR and U-series methods, have been discovered in the upper part of the Nihewan formation, a series of lacustrine deposits, in the Hutouliang Section, Nihewan Basin. The upper algal reef is composed of the columnar, laminar, and arched roofs.The lower algal reef is composed of the columnar stromatolites. The heights of the stromatolite in lower and upper reefs are 0.4～4.6m and indicate that the water depth of the stromatolite habitat was about 0.4～4.6cm.The structure of the stromatolite columns is characterized by altemations of light, intergranular pore-rich laminae and dark, organic substance laminae, indicating a day-night or seasonal changes in temperature. Abundant filamentous remains of algal,such as Phormidium sp. and Chroococcus sp., similar to the present species on the shores of the Caribbean Sea, Persian Gulf, Shark Bay （Westem Australia）, Solar Lake （Sinai）, and Walker Lake （Nevada）, have been discovered in the dark laminae. This indicates that during the Period of the stromatolites formation, climates in the Nihewan area might be as warm and dry as the present climate in the areas mehoned above.A PinusPicea-ArtemIjia pollen assemblage, indicate a wanner and drier climate and a forestgrasslands flora, been found in the stromatolite beds. The osewode shells （Limnocythere dbbiso, L. binoda, Ilyocypris tuberculata, I. salebrasa, merissa lacustris）,found in the stromatolite beds, indicthe a salt or sendrsalt wther environmenL The values of δ18O and δ13C in the upper part of the Hutouliang Section is characterized by a positive correlation. According to the variation of stable isotopic composition of carbonate in the lacustrine deposits, two higher value stages of δ18O and δ13C and two lower stages can be found in this section.Generally, the δ18O values of carbanate in 1acustrite sediment are controlled by that of precipitation, the latter has a positive correlation with temperature in turn. The δ18O and δ13C values hate a positive correlation with saltness, which has a positive correlation with evaporahvity, and the evaporativity has a posihve correlation with temperature and a negative correlation with humidity. The δ13C values have a positive correlation with relative density of the C plant in vegetation, and the density of the C plant has a negative correlation with the humidity, namely the drier the climate is, the higher the δ13C is. So the δ18O and δ13C of carbanate in lacustrite sediment can be used as indicators of temperature and humidity respectively. The higher values of δ18O and δ13C of carbanate in lacustrite sediment represent warmer and drier climate while the lower value of which represent cooler and wetter climate. The stromatolite layers have the higher values of δ18O and δ13C, indicating the more warmer and drier climates during the last interglacial period.In addition, the stromatolite beds have lower values of SiO2, Al2O3, Fe2O3, FeO,TiO2, K2O, Na2O, MnO, and P2O5 from the terrigenous clashcs, and the higher values of CaO, CaO / MgO, and （CaO + K2O + Na2O） / Al2O3 from the lacustrine chemical deposits. It indicates that the flora covered much of the land-surface and the more warmer and drier climates.