In the Reppe-technology process of producing 1,4-butanediol(BDO), a certain amount of viscous substrate is formed in the thin-film evaporator due to intramolecular aggregation of BDO. A process is proposed to recycle the substrate and reduce discharge. The substrate is hydrolyzed by H 2SO 4 solution at the conditions of mass fraction of H 2SO 4 is 15%, mass ratio of H 2SO 4 to the substrate is 1.3〖DK〗∶1.0, temperature is 150 ℃ and reaction time is 7 h. The results show that BDO based on the raw substrate can be feasibly recovered at the rate up to 39.1%.