In the Han Dynasty,the real estate business was extremely flourishing owing to three maim factors,namely the active merchandise economy,the real estate privately owned system and the limit of agriculture economy.

This article mainly takes how to correctly solve problems of the real estate dual sales as a center, analyzes to the legal question which involves in the practice of legal matter.

This paper mainly illustrates how to protect the benefits of prior purchaser in follow respects: the efficacy of contract for house dual sales ,the right of cancellation of the prior purchaser, the compensatory spheres of seller in breach of contract, the burden of risk of seller.