Based on the observations (1975-2010) at the Wusong Station, a typical tide station, the impact of variations in tidal level on tidal form was analyzed. The results show that the annual mean high (low) tidal level rises along with the rise of the an - nual mean tidal level, with significant linear correlation between them. However, there are no clear correlations between the tidal range, tidal duration and tidal level. In addition, there are no obvious correlations as well between the tidal level change and all extreme values, the annual highest (lowest) tidal level, the annual maximum flood (ebb) tidal range, the annual maximum (minimum) flood (ebb) duration, etc