Deterioration of fly ash concrete (FAC), high performance concrete (HPC), and high performance hybrid fibers reinforced expansive concrete (HPHFREC) subjected to combined action of flexural load and 5% magnesium sulfate solution is investigated. The change of dynamic modulus of elasticity (DME) was monitored and recorded as to observe the corrosion of concrete specimens in magnesium sulfate environment. Results show that in the initial exposure stage, the relative dynamic modulus of elasticity (RDME) of concretes increase steadily as a result of the reinforced effect of flexural load and nucleation of attack products, consequently the microstructure is compacted and the strength of the concretes is enhanced in some extent. As for the later corrosion proceed, the interior cracks occurred and the flexural load accelerated the degradation of concrete. HPC demonstrated good corrosion resistance when it was exposed to only magnesium sulfate solution, and HPHFREC showed the best stress corrosion resistance when it was subjected to combined action of magnesium sulfate solution and flexural load.