Based on the data of tidal stations (Nandu Station, Zhanjiang Port, and Beijin Port) in the coastal areas of western Guangdong.The Mann-Kendall method were used to test the trend and mutation of the annual highest tide level, and analyze the trend of tide level. The new results of design tide level of each station were obtained by curve-fitting Methodology in hydrological frequency analysis.The results show that :(1) The tidal level in the coastal areas of western Guangdong show rising trend, especially in Nandu and Beijin Port,with Z-values of 1.52 and 1.49, respectively. While changes at Zhanjiang Port are not significant. Each station has multiple mutation points, with typical mutation years being 1980 and 2011;(2) The frequency analysis results, extended with additional data, suggest that as the statistical parameters increase, the design annual highest tide level for various frequencies exhibit a certain degree of increase，among which the design tide level of 100-year increases by 0.35～0.5 m, an increase of about 10%.Suggestions were put forward to examine the defense capabilities of seawalls, accelerate the reinforcement construction of seawalls to meet standards, and examine flood tide water surface profile in the coastal areas of western Guangdong. The research results provide a scientific basis for regional flood and tide safety decision-making, as well as for the planning and construction of engineering projects.