Selecting 16 representative tidal stations in the Ningbo coastal area, annual maximum extreme value distribution method, annual highest tide level Pearson-Ⅲ distribution method, extreme difference ratio method, and high tide level synchronous correlation method were used to make frequency analysis. Then a chart of high tidal level in different coastal area according to the calculation results was developed, which can provide a construction reference for coastal engineering and design high tidal level of the area without observation data.