As ocean bill of lading is one of the most important documents of the international trade, using it right and legally will contribute a lot to the development of international trade. In the article, the author first described all types of risks concerning the B/Ls such as the anti-dated bill, the advanced bill, and then explored all the possible causes of the risks and finally worked out a series of measurements to prevent the risks like controlling the credits of the business partner, choosing the right trade terms and setting the proper clauses of the letter of credit.