The public rental house (PRH) plays a significant role in our housing security system. Using the theory of public goods, both government and private enterprises have advantages and disadvantages in supplying the PRH. In order to optimize the present supply system of the PRH, this article introduces the delivery pattern of public and private partnerships (PPP) into the government allocation system, and improves it into public-intermediary-private-partnerships (PIPP), a new supply system through government, private enterprises and intermediary organization cooperation. It helps to better achieve the security role of the PRH in our society.