With the gradual promotion of SF6/N2 hybrid insulating gas, the retired sulfur hexafluoride (SF6) gas will multiply dramatically, which needs to be strictly purified and reused in order to reduce carbon emissions. However, the existing purification methods are difficult to remove the low concentration of C3F8 impurities in sulfur hexafluoride gas, which greatly affects the recycling of SF6 gas. Based on this, this paper built a test platform to study the adsorption characteristics of C3F8 in decommissioned SF6 gas, adopts three kinds of commercially available molecular sieve materials to simulate the adsorption process of SF6 gas in GIS power equipment in the current engineering application, measures the adsorption performance of low concentration C3F8 (ppm level) impurities in decommissioned SF6 gas on molecular sieve materials, and screens out the optimal adsorption properties on molecular sieve materials by combining with SEM, TG, FTIR, and BET characterizations. Based on the characterization of SEM, TG, FTIR and BET, the best adsorption material ST-100 molecular sieve was selected. And on this basis, the adsorption performance of ST-100 on low-concentration C3F8 was investigated in accordance with the changing law of the mass of adsorbent, inlet pressure and inlet flow rate, and the regeneration and stability of ST-100 was verified through the adsorptiondesorption cycle. The results showed that ST-100 molecular sieve is an efficient adsorbent for C3F8, with the best adsorption performance at the temperature of 30 ℃, the mass of 1.5 kg, the inlet flow rate of 200 mL/min, and the pressure of 0.3 MPa, with the adsorption rate as high as 99%; and the adsorption rate was still maintained at 90% after five rounds of adsorption-desorption cycle tests, with good cyclic adsorption stability.