In order to explore the mechanical behavior of segmental precast prestressed composite box girder with corrugated steel webs，under the premise of considering the influence of construction technology and tendon ratios， three scaled model test beams were designed and manufactured for the experiment of mechanical behavior． The similarities and differences were compared and analyzed of the mechanical behavior between the integrally poured prestressed composite box girder with corrugated steel webs and the segmental precast prestressed composite box girder with corrugated steel webs． A calculation formula was presented of flexural bearing capacity of segmental precast prestressed composite box girder with corrugated steel webs． The results show that the stiffness degradation of the segmental precast beam is significantly greater than that of the integral beam after the concrete cracking，especially the segmental beam with only external tendons． The bending contribution of corrugated steel webs of segmental beam is significantly greater than that of the integral beam，particularly evident in the segment joints． The stress increment of external tendon of segmental beam is greater than that of the integral beam with a fast growth speed． Compared with the calculation formula of flexural bearing capacity of integral beam，the calculation formula of flexural bearing capacity of segmental precast beam presented in this paper is better in congruity with the test results