The reinforced concrete slabs using HRB500 rebar and ordinary steel rebar were corroded by artificial accelerated method, and four-point bending test was applied on these corroded slabs. The failure modes, flexural capacity, load-deflection curves of the slabs were analyzed by comparing test specimens under different corrosion degree. This study further investigated the relationship between corrosion ratio and deterioration of tensile capacity and bond behavior of corroded steel. Considering the occurrence of reinforcement yielding and bond-slip due to different corrosion degree, a calculation method of flexural bearing capacity of corroded reinforced concrete slab was proposed. A good agreement between calculated values and tested results of the corroded reinforced concrete slab was achieved. The average ratio of calculated values to test results was 1.019, and the standard deviation was 0.081.