The force analysis of the anchor chain system is a key point in the design of pontoon.According to the suspension chain theory，the calculation formulas for the anchor chain length and anchor chain tension are provided in Design Code for Wharf Structures.For the horizontal tensile force of the anchor chain in the formula，the code does not provide a corresponding calculation method.This paper analyzes the force state of the pontoon anchor chain system by setting different assumptions，proposes two simplified methods and the recommended methods based on static equilibrium analysis，and compares the calculation results of three methods through the case.The results show that the simplified calculation method considers the unidirectional force balance，which is only suitable for special conditions where the anchor chain angle is the same.The recommended method considers the force balance of the two directions of the plane，which is suitable for the general situation of different angles of the anchor chain.