This paper discusses the corrosion problem and the corrosion protection method of the corroded Reinforced Concrete (R.C.) structure, and provides some practical instances to illustrate the current corrosion situation of the existed R.C. structure. It is emphasized that we are wasting labour, time, money and decreasing the working life of the existed corroded R.C. structures that are dangerous to traffic and public safety. Improper design of R.C. structure in corrosion environment area and the ineffective method of corrosion protection to the corroded R.C. structure in Taiwan should be improved.