The invention belongs to the technical field of preparation of pentafluoroethane, and specifically relates to a purification process of chloropentafluoroethane. The purification process comprises thefollowing steps: extracting and mixing a mixture of CFC-115 and HFC-125 from a CFC-115 collection tank in an extraction column, returning a part of the mixture discharged from the top of the column toa heat exchanger inlet pipe in front of the extraction column to mix with the materials from the CFC-115 collection tank, and then adding the mixture into the extraction column again; and the rest ispure chloropentafluoroethane. The purification process of chloropentafluoroethane has the following beneficial effects: the purification process of chloropentafluoroethane can improve the purity of chloropentafluoroethane to 99.5% or more, the purification cost is low, the efficiency is high, and the incineration cost of the incineration process is reduced while the main product HFC-125 is recovered.