Abstract: Field investigations and statistic analyses on the existing data reveal that the modern Cobicula fluminea lives in fresh-mesohaline river-lacustrine conditions under the warm-humid climate, with annual average precipitation more than 800 mm (800~1 400 mm) and the average January temperature over 0℃ (0.5~4.5℃) in southeastern continental China. The shell records the climate situation and water property and the environments during its growth. δ¹⁸O and δ¹³C of shells taken from different areas and measured by mass spectrometer Finnigan MAT-253 show that there is very small δ¹⁸O differences between the shells living in the same area and the different areas with the comparable climate-environmental background. For example, δ¹⁸O among the shells taken from Yifan River,abandoned Yellow River from Jiangsu Province, Mianjiang River from Jiangxi Province and Lake Dianchi from Yunnan Province is only around 1.4‰. δ¹⁸O in different layers in the same shell is one of the proxies of the seasonal temperatures. The average value of δ¹³C from various areas indicates that there exists a general trend of decrease along the latitudes. δ¹⁸O and δ¹³C values of shells from Yifan River and abandoned Yellow River in Jiangsu Province with a warm-humid season possess a similar change procedure, indicating that δ¹⁸O and δ¹³C are in immediate response to the regional climate changes.