With the rapid development of urbanization in coastal areas, many municipal solid waste landfills tend to be built near shorelines. Complex hydrodynamic conditions like tidal fluctuations may affect the heavy metal transport of landfill leachate in sedimentation beach groundwater system. In order for making an analysis of tidal effects on groundwater movement and heavy metal transport, regular field observations were conducted and a field data calibrated numerical model of groundwater flow field in a seaside landfill site based on the SEAWAT model was presented to simulate heavy metal transport. It is concluded that both the groundwater table and the concentration of heavy metal pollutants fluctuations induced by the tide possess the characteristics of phase lag and amplitude attenuation. Pollutants travel about 34 m farther and 20% more towards the sea when tidal effects are taken into account. The results can provide a theoretical basis for controlling the heavy metal pollution and protecting the coastal resources and environment.