Combined with a freeway widening project, an old bridge composed by simply supported prestressed concrete hollow slabs in 20m span was detected in-site for deciding whether it can be further used, which was designed according to the former design code. The maximum test load was calculated under the worst load combination at service stage according to the current design code. The inspection of the bridge was conducted by nondestructive testing methods for strength and carbonation of concrete, concrete cover and corrosion of prestressed strands. The service behaviors such as crack and mid-span deflection of a slab were measured by static loading test. The entirety of the bridge was detected by dynamic loading test. The results show that the strength of concrete and the concrete cover of prestressed strands meet with the design requirement, the carbonation of concrete and corrosion of prestressed strands is insignificant, the bridge is in good service performance, and the slab has enough flexural stiffness to prevent larger deflection.