Abstract ： Research purposes ： The earth pressure algorithm of gravity shoulder retaining wall under vertical loads of train in railway engineeringusually comes from the subgrade manual. And that can also reference the 11 diffusion angle 450 gmethod" or 11 diffusion angle 45° + !/2 method". But all the algoritlims above are inadequate. This paper put forward a new algorithmthat can be named" three rupture angle method" . The new algorithmcan make up the deficiency of the above algorithms. And the results of the new algorithm are more reasonable， that can provide reference for engineering designers. Research conclusions ：( 1) The scope and intensity of soil pressure by subgrade manual method changes with the height of the wall. ( 2 ) The "diffusion angle 450 method" and "diffusion angle 45° + !/2 method" can make up for the deficiency ofsubgrade manual method. But the two methods still using the simple assumptions and the influence of the filler or the boundary conditions are not considered. (3) This paper put forward" three rupture angle method "that can make up the shortage of the above algorithm. The influences of filler properties and boundary conditions on the range of soil pressure were fully considered. The calculation results are more reasonable. (4 ) The 11 three rupture angle method11 can be used in railway subgrade gravity retaining wall design. And it can also be used for other shoulder wall or embankment wall design. The design results are more reasonable and reliable.