Abstract: The Archaean buried hill reservoir of Bozhong (BZ) 26-6 Structure has strong heterogeneity, uneven distribution of oil and gas, and complex fluid properties. In order to solve the difficulties in determining the fluid properties of the Archaean buried hill and the reservoir water content during drilling, a method for identifying the water content of the buried hill reservoir was developed. By analyzing the characteristics of gas logging, three-dimensional, geochemical, and infrared spectroscopy, and other logging technologies in data and spectra of oil and water layers in the buried hill operation section of Bohai Oilfield, a differentiation chart and standard spectrum of oil and water layers were formed based on the fluorescence drop illumination and fracture development. In addition, a method for identifying water content in the Archean buried hill reservoir in the BZ 26-6 Structure was established. The method was applied in eight wells of the BZ 26-6 Structure. The study achieved 100% accuracy in identifying the water content in the reservoir and the judgment of the depth of the oil-water interface was consistent with the test results, attaining positive on-site application results. This method can provide an important basis for exploration decision-making and has great promotion and application value.