We differentiated the sandy coast of South China into three basic types of coastal geomorphology: cape-bay coast, barrier-lagoon coast, and straightened coast. After analysis on regional variations of the dynamic environment along the modern coast of South China and comprehensive comparisons among on-the-spot observational data in different seasons from different foreshore profiles of the sandy coast situated on different geographic coastal sections, the morphodynamic characteristics of the sandy beaches along the coast of South China were explored. The tectonic movements and sea level changes occurring during the regional geologic historical processes lay down a basis for the development of large-scale sandy coastal geomorphology. After the postglacial, sea level was relatively stable. Under recent coastal dynamic conditions, the scouring-silting adjustment made by the actions of supply, migration, and accumulation of the sandy beach sediments made decisive effects on the state of the beach face. Among them, the wave-tide index (K value) is an important indicator that reflects these changes. The K values of sandy beaches along the coasts of South China are generally more than 1. Most of the sandy beaches are predominated by wave-dominated geomorphology, with a rather great beach face gradient. There correlation between the K value and seasonal deformation degree of the sandy beach is positive. The grain size of the beach face sediment is closely related to the K value and also is affected to a smaller extent by the seasonal changes of wind wave and the geographic distribution of the various shorelines.