Twenty-eight coastal tidal gauge stations are applied to calculate the annual design highest tidal level of coastal area of Guangdong province. The data of these stations are checked in credibility, coherence and typicality. The series of the data can meet the requirement of related standards. The extreme values of these stations are treated. Pearson type three distribution ( P-Ⅲ) and extreme value type one distribution are employed to calculate the annual design highest tide level in coastal area of Guangdong province. The best distribution is selected through comparison of curve fitting. The average values of the annual highest tidal levels in Guangdong coast is increased from east to west, which is same with the change of tidal range. The Cv of coastal stations, more than 0.20 in general,is bigger that of estuarine stations because the Cv is affected greatly by storm surge. The annual design highest tidal level in east Guangdong coast is lower than that of west Guangdong coast. The highest occurs in the west Guangdong coast, where the tidal range is the biggest and the storm surge is more frequent, the lowest occurs in east Guangdong coast, where the tidal range is small, such as Gangkou and Shanwei stations.