The mean longshore current distribution has a significant impact on coastal discharge and sediment transport.In order to study the distribution characteristics of mean longshore current more deeply,especially under steep slopes rather than mild slopes,base on the 140 steeper-slope mean longshore current experiment,this paper searches for the curve fitting of mean longshore current distribution,which is different from Allen distribution and suitable for steep slopes.The results show that using the self-defined piecewise function and the appropriate constraints can better fit the distribution characteristics that the coastal side of the mean longshore current distribution shows a convex trend under steep slopes.