There are 231 fishing ports and harbors along the coast of Taiwan now and utilize the phenomenon on the low side of function as to some fishing ports and harbors. This research intends to investigate a practical evaluation index for breakwater reduction based on the functions of fishing ports and the re-utilization of coastal space, the factors of security of fishing ports, fishing environment, development of tourism and some other factors are taking into account while evaluating the breakwater. In the research approach, the statistic data of usability ratio on the breakwaters at the fishing ports in Taiwan is first summarized. Then, to investigate the visiting scholar different fields, such as expert, government's fishing policy unit and fisherman's group, etc. The factors for evaluating breakwater reduction and the weighting number for the standard quantification of evaluation indices are proposed and the feasibility is confirmed with the statistic analysis. Furthermore, the evaluation criteria for the implementation of the construction methods of breakwater reduction in a fishing port is devised, and the breakwater reduction at Hemei Fishing Port is taken as a demonstrative example to analyze the achievement of reduction work, hoping to provide the reference basis for the fishing port facility reduction works evaluation by each level of fishery authorities and to achieve the requirements of the policy for the reduction of water-breaking to construct the decrement of things.