Ujung Beach is a tourism spot in Sibolga City that has abrasion problem that can be harmful for activities of people and facilities around the coast. Therefore it is necessary to analysis of wave transformation and solve that problem. This study is to analyze wave transformation for the planning offshore breakwater with CGWAVE simulation with existing conditions and breakwater structure. In this study, the writer modeling bathymetry data, water level analysis, wave return period of 50 years, and breakwater dimension. From the results of the CGWAVE simulation, dominan wave angel is from 225 o each parameters wave height, wave velocity, and sea water surface on existing condition that reach the coastline are 1,12 m, 1,54m/s, dan 0,51 m. After the addition three series of offshore breakwater structure that have length 80 m, gap 20 m, located in depth 3-4 m from mean sea level and 250 m from the coastline can reduce each parameters of wave height, wave velocity, and sea water surface are 26,45%, 32,72%, dan 38,15%. From these data the design of breakwater effective to solve abrasion in Ujung Beach.