In recent years， Chinese enterprises， in overseas investment， adopted the method of state contract， signing the contract with the government of developing countries with rich natural resources， in the field of natural resources. In the event that the state action by the host country violates its obligations under the state contract， such action may be the violation to the host country ' s promise under the bilateral investment treaty between the host country and the home country， therefore the overlapping of contract claims and treaty claims occurs. In this paper， the author， by a couple of cases awarded by ICSID， analyzes the legal issues of overlapping of contract claims and treaty claims， and then puts forward some suggestions to Chinese government in its singing of bilateral investment treaty with other countries.