The morphological evolution of the sand barrier in the Anhaiao coastal zone of Pingtan from 1996 to 2018 was studied. Tidal correction was used to refine the location of the coastline. A standard deviation ellipse method was applied to further analyze the movement of the barrier head with the axis and rotation angle. A natural neighbor interpolation (NNI) method was carried out to calculate the terrain of the intertidal area, and the erosion and deposition characteristics were illustrated based on the terrain. The results showed that the northern part of the sand barrier facing the lagoon area was deposited over the whole studied period, while erosion has always occurred in the southern part of the sand barrier facing the open sea. The erosion and deposition were slightly different on both sides of the barrier head due to hydrodynamic turbulence. The middle sand barrier moved 102.60 m away from its original location in 1996, and the end of the barrier moved 65.45 m. The head of the sand barrier continued moving 379 m to the northwest. Consequently, the preliminary morphological evolution of the sand barrier corresponding to the distance and direction of movement was detected.