With the rapid development of city rail transit, prestressed concrete U-shaped beam has been widely applied because of its own advantages.The U-shaped beam has been applied in shanghai subway line 6,guangzhou subway line 2 and Nanjing subway line 2. However the spatial stress of U-shaped beam is complex, there isn’t relative design criterion in our country. based on actual engineering as a background, the paper usd ANSYS finite element software to analyze the nolinear elastoplastic behavior of U-shaped beam. It also analyzed the deflection strength of reinforce and concrete of U-shaped beam under different load conditions. The value of deflection is compared with experimental value under 1.0 time span moment load. Finally, 3.37 times span moment load is taken as the ultimate bearing capacity value. Compared with 2.0 times design load, the value is safer. The result can provide the basis for the design theory of U-shaped beam.