Abstract: In order to study the simple and quickevaluation method of volumetric water content in diesel oil-contaminated sands, different proportion of diesel oil and /or water were first artificially added and mixed with initially dry clean sands to prepare organic contaminated soil of different contamination degree. Then Time Domain Reflectometry(TDR)tests were conducted on the sands to study the relationship between the dielectric constantsof the sandsof certain dry density to their water and oil content. Test results indicate that there's siginificant delay in the TDR reflected wave if the sands contain only deionized water or mixture of deionized water and diesel oil, and the calculated dielectric constant increase with the increase of water content. When only diesel oil is contained in the sands, TDR reflected waveform will be slightly delayed with the increase of oil content. Furthermore, the calculated dielectric constant also increases with the increase of oil content. Thus, TDR test can be used for quick detection of the contamination degree of diesel oil contaminated sands.