Summer monsoons (South Asian monsoon, South China Sea monsoon and Sub-tropical monsoon) are prominent features of summertime climate over southern China. Dif-ferent monsoons carry different inflow moisture into China and control the temporal and spa-tial distributions of precipitation. Analyses of meteorological data, particularly wind, tempera-ture and pressure anomalies are traditional methods of characterizing moisture sources and transport patterns. Here, we try to utilize the evidence from stable isotopes signatures to trace summer monsoons over southern China. Based on seven CHNIP (Chinese Network of Iso-topes in Precipitation) observatory stations located in southern China, monthly composite precipitation samples have been collected and analyzed for the composition of δ¹⁸O during July, 2005. The results indicated that the spatial distributions of δ¹⁸O in precipitation could properly portray the moisture sources together with their transport pathways. Moreover, the amount effect, altitude effect, temperature effect and the correlation between δ¹⁸O vs. relative humidity were discussed.