Need. If the pre-camber design is too large, the bridge deck pavement will be thick at both ends and thin in the middle when it is constructed according to the design elevation. With the increase of beam creep, the smoothness of bridge deck will not meet the requirements, which will seriously affect the engineering quality of bridge deck. If the pre-camber design is too small, it will affect the stiffness of the beam, lead to difficulties in traffic regulation, increase vehicle impact and cause severe vibration of the bridge. Therefore, in the construction process of cast-in-place prestressed beam, the pre-camber should be strictly controlled. The factors affecting the pre-camber are the elastic-plastic settlement of the bracket foundation after loading, the anti-camber of the beam caused by tension, the deflection caused by concrete shrinkage and creep, and the elastic deformation caused by the bracket under construction load.