The confirmation of the design tidal level is an important and basic task in coastal port engineering. For a new port with short-term observed tide data only, the difference-ratio method and correlation analysis are used to calculate the design high/low water level, while the correlation analysis and K-value method to calculate the extreme high/low water level by long-term observed tide level data of the standard port nearby. This paper proposed quantitative indicators for judging the tidal similarity firstly and the method for determining the design tidal levels based on several calculating results for different models. The proposed model has been applied to the general plan of Pikou port area, and the result has provided a reference for the determination of design tidal level of new port areas.