The general protection methods against anchor dropping and a new type of flexible protective mattress for submarine pipeline crossing shipping channel are presented, and the application characteristics of these protection methods are compared. According to a project, the single and combined protection methods used to defense the failure from anchor dropping are proposed, and the test for the anchor dropping is carried out. Based on the test data and design code, the influence of anchor dropping on the strength of the submarine pipeline is evaluated, and the optimal protection scheme for the submarine pipeline is given according to the check results. The basis for engineering design and offshore construction is provided.