Grain size distribution of marine sediments is an important indicator used for various topics in sedimentology,environmental change and many other fields.However,current methods of grain size determination are either very labor intensive or lack of accuracy.Feasibility of using major element compositions as proxies of grain size distribution for tidal flat sediments was studied.One hundred and fifty-two tidal flat sediment samples from coastal areas of East China Sea were collected and analyzed for grain-size distribution and major element composition.The results showed that the contents of sand,silt,clay and the median of grain size were significantly correlated with major element concentrations of sediment samples.The contents of silt,clay and the median of grain size are positively correlated with the contents of Al,Fe,Mg and K while the content of sand is negatively correlated with the content of Si.The regress equations were obtained to predict grain size parameters using major element compositions.It is proved that using major element compositions as proxies of grain size distribution for tidal flat sediments is feasible.