Abstract: Influenced by many factors, such as borehole condition and drilling fluids, the lithological profile obtained by the conventional logs will be in disagreement with the actual, resulting in poor accuracy in calculation results of reservoir porosity, and even failure in fluid property identification. ECS (Elemental Capture Spectroscopy) is a new well-logging technology developed by Sch-lumberger used for obtaining the formation elements, which can obtain accurate clay contents and clay types, obtaining better lithology profile. Besides, the ECS can be used to calculate the porosity accurately, improving the coincidence rate in logging data interpretation by combining with compensated density and compensated neutron log. In this paper, the principle and instrument parameters of ECS are introduced, and the advantage of ECS is described. Through application in SZ36-1 oil field, it has proved that ECS is very successful in logging data interpretation, and significant in application.