Through mathematical analysis,the principle of risk liability-gain was proved,when the expected risk gain exceeded the risk liability in the process of making decision,the decision maker had a preference to take risk,and when the expected risk liability to take on exceeds the risk gain, the decision maker tended to be risk-aversion.

According to significance and the order of implementation at one stage,the national interest of China have been graded into development interest,sovereignty interest and responsibility interest.

Through mathematical analysis,the principle of risk liability-gain was proved,when the expected risk gain exceeded the risk liability in the process of making decision,the decision maker had a preference to take risk,and when the expected risk liability to take on exceeds the risk gain, the decision maker tended to be risk-aversion.

Legislators should balance interests of both parties through just distributing risk liability of traffic accidents, based on rule of law and human rights, so as to fully realize social interests and to attain the goal of keeping traffic order.

Through a case of geotechnical investigation quality defects leading to increasing contractor cost,analyzed the quality liability and the risk liability of lump sum contract.

Venture transferring and liabilities ascertaining are always hinged upon the application of principal of delivering in international goods trade.