Housing pre-sale, also known as commercial housing pre-sale and uncompleted residential flats pre-sale, refers to the real estate transaction behavior that the real estate development enterprise and the purchaser agree that the purchaser will pay the deposit or advance payment at a certain date in the future and own the existing house. Its essence is the buying and selling of housing futures, which is just a futures contract of housing. It and existing home sales have become two main forms of housing sales in China commercial housing market.