Abstract: To reduce energy consumption and take full use of energy in the technological air conditioning system in a cigarette factory, a system for recovering waste heat from cooling water was designed based on heat pump technology. The system consists of a heat pump unit and water pumps at its hot end and cold end. The cold end of the heat pump is connected to the cooling water circulation pipeline of the refrigeration system, and 20%-25% of cooling water is diverted to the heat pump to recover the low-grade heat energy in it. The hot end of the heat pump is connected to the circulating water pipeline of the reheating system to heat 80%-90% of circulating water and thereby reduce the steam consumption of the reheating system. The designed system was tested on the air conditioning system in aging warehouse in Hangzhou Cigarette Factory. The results showed that the ambient temperature and humidity in the aging warehouse did not change significantly, the daily steam consumption of the reheating system was basically zero, and the average daily COP of the refrigeration system increased from 2.82 to 4.03. Compared with the same period in 2021, the energy efficiency index of the technological air conditioning system raised from 2.28 to 5.05, the average daily steam consumption decreased by 33.65 t/d, and the electricity consumption decreased by 6 087 (kW·h)/d, it saved about 2.24 million RMB yuan every year. This technology provides support for the energy utilization promotion and production cost reduction of cigarette factory.