Sediment samples from Dianchi Lake sediment core were measured by means of the direct γ ray analysis for the sediment-depth profiles of natural radionuclides 210 Pb and 226 Ra and artificial radionuclides 137 Cs and 241 Am. The 226 Ra activity provides a direct measurement of supported 210 Pb activity for each sample analyzed

and the 137 Cs and 241 Am activity may provide independent age markers. The sediment core was dated with 210 Pb by using a constant rate of supply（CRS） model and the results were consistent with additional dating evidences from the artificial fallout nuclides 137 Cs and 241 Am. The study indicates that the sediment accumulation rates of Dianchi Lake were varied significantly during the past 100 years and had an accelerated accumulation rate in recent several years.