Objective: To evaluate the impact of national centralized volume-based drug procurement on the agreed procurement cycle and renewal period daily cost in public medical institutions，so as to provide scientific evidence for Policy synergy. Methods: Based on the Interrupted time-series analysis (ITSA) with two intervention points，the change of purchase volume，expenditure and daily cost of policy-related drug in the public medical institutions from 7 pilot cities during January 2018 and July 2020 were analyzed. Results: The changes in procurement volume and its share of the level of the pilot period for the original drugs and the generic drugs did not pass the CEQE among the centralized volume-based drug procurement are all decreased (P＜0.05). The change in the level of the daily cost were statistically significant among original drugs ≤ft(β₂=-0.58，P=0.043\right)，generic which passed the CEQE ≤ft(β₂=\right. -3.18，P＜0.001) and generic which did not pass the CEQE ≤ft(β₂=5.83，P＜0.001\right) in the pilot period. The procurement amount ≤ft(β₃=\right. 19.69，P=0.025) and the proportion of generic which passed the CEQE during the pilot period were all increased，while the procurement amount and the proportion after the intervention were all decreased. Different ATC classified drugs of selected drugs showed that the levels of anti-infective drugs，anti-tumor and immune drugs increased significantly (P＜0.05). Conclusion: It needed to strengthened clinical drug use monitoring and management，design and improve the supporting measures such as price monitoring，adjustment of medical insurance payment standards.