Abstract: Maowei Sea of Beibu Gulf is an essential economic development zone in southern China, constructed with several ports and terminals. Recently, the coastline has been heavily reclaimed. Here, we developed a two-dimensional hydrodynamic numerical modeling system to analyze the impact of reclamation and port construction between 1985 and 2020 based on the comparison of three important tidal dynamic parameters, i.e., tidal elevation difference, main astronomical tidal components, and tidal flux for the safe development of local hydrodynamic environment in Qinzhou Bay. Results show that the tidal difference is small but slightly increased around 0.07 m after the reclamation. The primary diurnal tidal component K₁,O₁, semidiurnal tidal component M₂andS₂ are the major driving forces on the tidal forcing in Qinzhou Bay as it slightly increased by 0.02-0.03 m after reclamation. The reclamation maintained the deep channel by constraint the flows, thus flushed the depositions. K₁andO₁ are important tidal dynamic parameters affecting Maowei Sea. Sensitivity test shows that the construction of Sandun highway, coastal reclamation of Qinzhou Bay and the construction of nuclear power plant have increased the tidal difference in Maowei Sea for 60%, 20%, and 10%, respectively. Consequently, the reclamations improved the regime by narrowing the channel, and the peak flux of the three waterways in the outer Qinzhou Bay has increased significantly favoring to some extend the navigation and maintaining the stability of the main channel. Therefore, from the perspective of tidal dynamics regulations, the current coastline reclamations foster a good development of the bay regime in view of little disturbance on tidal dynamics, optimization of local hydrodynamic environment and the improvement of navigation safety.