Organic contamination in groundwater and the impact on human health have been a growing concern. In the study of organic chlorine pollution, applying chlorine isotope (37Cl) can be applied to identify pollution sources and to study pollution mechanism at the atomic level, providing a favorable tool for more effective work on the organic pollution of groundwater. In this paper, eight kinds of chlorinated VOCs chlorine isotopic testing methods and techniques were discussed on the basis of the literatures information at home and abroad. And some applications of the chlorinated VOCs chlorine isotopes were shown, including the identification of groundwater pollution sources, monitoring the process of degradation of organic pollutants, verifying results of the restoration measures, distinguishing the manufacturers of Chlorinated VOCs and tracing the migration and the mixing process of chlorinated VOCs in soil and water. Advanced testing process should be developed and studies should be carried out on the mechanism of organic chlorine isotopes fractionation as soon as possible in China. At the same time, the use of C and Cl isotopes technology in chlorinated VOCs contamination and restoration should also be enhanced.