Based on theoretical analysis, this paper selects panel data from 31 provinces （due to the lack of data, the statistical data mentioned here do not include the Hong Kong Special Administrative Region, the Macao Special Administrative Region and Taiwan Province）in China to study the impact of population aging on the effectiveness of monetary policy. The results show that the aging of the population significantly weakens the effectiveness of monetary policy. From the perspective of regional heterogeneity, the more severe the population aging, the stronger the inhibitory effect of population aging on monetary policy. Further research finds that population aging affects the effectiveness of monetary policy by weakening the credit channels of monetary policy. Finally, it is proposed that the age factor of the population should be fully considered, and the relevant policy suggestions should be carefully evaluated such as the intermediary target and the prediction effect of monetary policy.