Concrete bridges are chosen to build bridges with short spans because the properties strong concrete structures for compressive force, but waek in resisting tensile forces. The new technologi have way to resolve the weakness of concrete, that is with gives tension to the concrete through a strands that is called prestressed concrete. One of common girder used to build bridges or flyovers is the box girder. The present study aims to get an effective cross section of box girder variation to be apllied on bridge construction. Three variations of this box girder have the same area and number of strands, so the result of this study can be compared. This study method is processing and data analysis with microsoft excel. The results of the stress values (initial condition, final condition and effect of the load) has a maximum prestrssed values is box girder type 3, meanwhile on deflection values (initial condition, final condition and effect of the load) minimum values is box girder type 3.