Using the improved ECOM model and suspended sediment transportation model, the impact of the estuarine funnel shape on the estuarine turbidity maximum zone formation is studied with an idealized strait and funnel-shape estuary designed in this paper. There exists turbidity maximum zone at stagnation point, and its center locates at south side of the river coast. The reason of formation of estuarine turbidity maximum zone was revealed in terms of dynamic mechanism. Compared with the case of the strait estuary, the current divergence induced by the spreading width of funnel-shape estuary inner the mouth makes the current weaken, the distance of land-ward flow of density current at bottom layer induces, and the saltwater intrusion strengthens in the funnel-shape estuarine area. In addition the landward density induced current of bottom layer and its westward flowing distance increases. The westward intrusion distance of saltwater in the strait river channel region increases. The concentration of suspended sediment in the funnel-shape estuary decreases, but there are two turbidity maximum zones in it. One lies in the strait river way. Because the stagnant point moves toward upstream, its position relevantly moves toward upstream. However, the other lies in the south coast of the funnel-shape estuary area. It is mainly induced by the river flow, which turns toward the south coast under the effect of Coriolis Force, and the bottom transverse circulation which transport high concentration suspended sediment to the south coast. The variation of the river mouth shape has obvious impact on the estuarine circulation, the salinity intrusion and the turbidity maximum zone.