Abstract: Volume factor and gas oil ratio are two of the most important parameters in oil reservoir evaluation and engineering. Due to the large intermediate component content of volatile crude oil, volume factor and gas oil ratio measured from single degassing and multiple degassing experiments are larger than those measured under field conditions. This paper compares the processes and data of degassing experiments, and analyses the reasons leading to the differences between experimental results, then proposes a correction method for converting the intermediate components of well fluid lost in degassing experients into liquid phase and builds the conversion formula. The corrected volume factor and gas oil ratio can more accurately reflect the actual characteristics of reservoir fluids in the production process of the mine because the influences caused by the lost of intermediate components is eliminated. The results show that the typical black oil experimental data can be directly used for engineering calculation, but the volatile crude oil data needs to be corrected. The stronger the volatility of crude oil is, the smaller corrected data of comparative experiments is. The calculated geological reserves are 6% to 10% higher than the volume factor measured under laboratory conditions.