Abstract: In order to improve the saturation of low-permeability reservoir core, the saturation method and experimental device were developed based on CO₂ displacement of absorbed gas. The saturation effect was investigated by the measurement of saturated porosity with the employment of 26 cores from low-permeability reservoirs. It was demonstrated that saturation effect was significantly improved and was close to complete saturation because the saturated porosity of the new saturation method was 0.54% on average larger than that of the traditional saturation method and 0.14% on average smaller than helium porosity. Also, it was illustrated that the new saturation method had highly pertinence in reducing the effect of absorbed gas in tight cores and was able to be widely used for the saturation of low-permeability reservoir cores because the relative increment of saturated porosity by the new method increased positively with shale content and negatively with average grain size, helium porosity and permeability.