Abstract: In order to better meet the needs of trade settlement, clean utilization, and carbon emission accounting for energy materials, and to improve the measurement accuracy and precision of the calorific value of combustible materials, a high-precision adiabatic oxygen bomb calorimeter based on vacuum Dewar bottle technology was developed. This paper introduces the basic structure and working principle of the calorimeter, and proposes a suitable testing procedure and method. The calorimeter's heat capacity and the calorific value of combustion materials were tested using benzoic acid (SRM39j) from the National Institute of Standards and Technology (NIST) as an example. The error uncertainty of calorific value indication was evaluated, and the linearity of the temperature circuit, the effective range of calorific value, and the environmental adaptability of the calorimeter were discussed. Test data show that the relative standard deviation of heat capacity is 0.047%, the change over three months is 0.138%, the calorific value indication error for benzoic acid is 17.8 J·g⁻¹, and the expanded uncertainty of measurement is 27.8 J (k=2). The linearity of the temperature circuit is 0.99993, the effective testing range is 15800-37000 J, and the environmental adaptability of the calorimeter needs to be improved.