Abstract: Large scale deepwater structures often face some complex natural conditions such as deepwater， large wave height and strong current， and are subject to considerable horizontal wave-current forces. It is necessary to accurately consider the size of the wave-current forces in the engineering design. A series of wave-current forces experiments for cylindrical， square columns and rectangular columns are carried out in the wave-current flume. At the same time， boundary element method for solving the wave loads on a large scale cylinder is used， and the preparation of Fortran program is made. Comparing the model results with the calculated values， an engineering method for calculation of the wave-current forces is developed： for deepwater large scale cylinder structures, wave-current forces can be obtained by the wave force linear superposition current force multiplied by 1.04， wave element is considered under the influence of current， and current force is calculated by flow around cylinders theory. By using this method to calculate wave-current force, and comparing the physical model results, the error is relatively small, and the model accuracy satisfies the requirement of engineering design.