Abstract: 157Gd complex (Cl3) tracer have a good physical and chemistry characteristics in well logging. The capture crosssection 4.87×10-20 cm2 is 64.16 times of common 10B tracer using at the moment. The chemical property is stability. It takes advantage on adaptability for hightemperature, highpressure of oil reservoir and coexistence of oil/water and various elements. It hasn't abnormally response on human, instrument and tubing. 157Gd complex tracer has been used in well logging on Daqing, Zhongyuan and Nanyang Oilfields. Adopting an important measure according the logging interpretation results, the stimulation effect is obvious.