Abstract: Based on comparison of the two categories of foraminifera fauna living on the modern open muddy tidal flats in the west coast of Bohai Bay, with or without chenier ridge, the authors thoroughly studied the variability indicating sea level elevations by different foram assemblages in these two kinds of environment. Each category of forams, consisting of five assemblages and corresponding to five subzones, i.e., high salt marsh, low salt marsh, upper intertidal, upper-middle intertidal and middle-lower intertidal subenvironments, was separated successively by MHWST, MHW, MHWNT and MSL, and investigated in detail. As a result, the specific forams-attached sediment from each subzone on tidal surface can be recognized as a high-accuracy sea level indicator, of which the reconstructed elevation point lies in the middle of the subzone with an error of half of the vertical range. It is evident that the existence of the local chenier body can exert an influence on the composition of foram assemblages, and such an influence tends to decline gradually from high to low water, and finally fades out seaward beneath the MHWNT.