Taken Lanzhangtian Bridge as engineering background, used ANSYS to simulate whole construction process refinement of numerical analysis. The results show that the crack resistance check in service ability limit state according to Code for Design of Highway Reinforced Concrete and Prestressed Concrete Bridge and Culverts, full prestressed concrete's normal section in the combination for short-term action effects allow certain tensile stressσst－0.8σpc≤0.1ftk. Combined with concrete biaxial pull-pressure strength interval in Code for design of concrete structures, when the tension is very large, concrete may also exceed strength envelope and destruct even compressive stress level is low. So according to the Code for Design of Highway Reinforced Concrete and Prestressed Concrete Bridge and Culverts, the compressive resistance check of bottom plate should also meet transverse normal section pressure stress limit σ≤0.6ftk.