Through centrifugal model test on sheet pile retaining wall for expansive soil embankment in Yumeng Railway,simulation test is carried out on reinforced embankment and unreinforced embankment,the optimum water content and rich water content.It is known from result that reinforcement for weak expansive soil embankment has significant effect,which effectively controls embankment deformation and satisfies design requirement.The changes of water content in weak expansive soil have great influence on embankment deformation.