Abstract: The mid-deep strata in the Tahe area cover the range from T₇⁵¹ to T₇⁸, that is, from the lower part of the upper Yingshan Formation to the lower Yingshan Formation from stratigraphic aspect. It is relatively difficult to track T₇⁵¹ with seismic and logging methods. Through a large number of statistic findings, three highly radioactive intervals were commonly found in the mid-deep formation in the Tahe oil field, with possible good reservoirs. Thus during the evaluation of mid-deep reservoirs, Natural Gamma Ray Spectrometry Logs is an effective technique to evaluate highly radioactive reservoirs. Highly radioactive formations not only can be a key horizon for regional formation comparison, but also a good indicator for fault belt, karstification and the path of oil and gas charging.