Based on the monthly panel data of 30 cities in China from 2015 to 2019, difference in differences model (DID) is used to analyze the impact of the Renting and Purchasing Policy on the volume and price of housing sales and rental market. The empirical results show that the implementation of the policy has a significantly positive effect on both the rental prices and volumes in the housing rental market, yet it reduces the sales volume of houses to a certain extent and restrains the rise of housing prices. The effects of the policy on the housing market have the transmission mechanisms from the rental market to the sales market, and from housing quantity to housing price. The conclusion shows that the effect of the policy has a time lag after the trial implementation, but it has played a positive impact on optimizing the structure of the housing market. It is suggested to further increase the supply of rental housing in the future, strengthen the regulation and supervision on the development of the rental housing industry, improve relevant laws and regulations, and expand public inputs to protect both the rights of the house renting and purchasing groups. More attention should be paid to the interaction between the prices and volumes of both rental and sales markets while planning and implementing housing policies.