Abstract: This article simulates the hydrodynamic environment of the Laizhou bay during 2000 and 2014 by MIKE21FM numerical simulation method.Compared with 2000, the results show that the marine engineering cause the change of topography and shallows of the Laizhou bay, which leads to the tidal current slowing down and the direction turning in 2014;the ocean current changed in the range of 1 cm/s to 3 cm/s with the constant northeast wind, the variation of coastline had little impact on the flow of the surface sea water; the storage capacity of tidal was 0.1788 km³, 3.2% decrease in 2000;the half water exchange time increased from 27.5 days to 29 days, which indicates the construction had little influence on the water exchange.