To investigate the structural behavior of segmental precast prestressed concrete box girder the regular service stage and the construction state, a span of 48 m full scale box girder model of this type was tested for the Fourth Nanjing Yangtze River Bridge approach. The assembling and loading plans were determined according to the geometric parameters as well as the actual constraints of the girder. This paper focuses on the static performance, such as stress and displacement changes of the girder during segment loading and transporting. Comparative finite element method analysis was also performed for checking. The model test results show that at the regular service stage, the residual deformation of the girder after unloading is small, which demonstrates that the girder keeps in elastic during loading. The tooth joints of segments work well with each other and have no relative slip; the global performance of the girder is good as monotonous. The vertical distribution of longitudinal strain at joint and between joints basically accords with hypothesis of plane section. Also, the stress increment of prestress tendons is linear to the mid-span moment change. Finally, during the segment transport stage, it shows that there is sufficient compressive stress of the lower flange of the girder to meet the security requirements of transporting girder.