Corrosion of reinforcing bar (Rebar) is the most important factor of reducing the durability of reinforced concrete structures and causing heavy losses. Optical fibre is an ideal sensing element for long-term monitoring. It has the advantages such as high durability, high stability, anti-electromagnetic interference, multiple parameters and distribution measurement. In this paper, based on optical fibre sensing technology, the rebar corrosion expansion in concrete was monitored and tested, and the numerical simulation of corrosion-induced cracking on concrete cover was performed. By simulating the corrosion-induced microcrack propagation in the concrete cover, the radial displacement at the time of cover cracking was used as an indicator to numerically analyse the effects of the three variables: concrete cover thickness, concrete strength and rebar diameter on the uniform corrosion of reinforcing bar. The radial displacement increases linearly with the tensile strength of the concrete. When the rebar diameter and the concrete strength are constant, the radial displacement at the time of cover cracking increases as the concrete cover thickness increases.