Abstract: Whether it is called administrative contract or civil contract,the equality and balance between duties and rights of all parties of the contract of assigning the usufruct of sea-zone between all levels should be maintained.If we describe the nature of the contract as administrative contract,the rights of the usufruct may be violated by all levels of the Maritime Bureau because there are no system in China to keep the balance of the parties’ interests,like that does in France.So the best way is to interpret the contract as civil contract.

Key words: the contract of assigning the usufruct of sea-zone, administrative contract；civil contract