To assure operation safety and extending service life of port facilities, sheet/pipe piles of wharf at Hwa-Liang, Kee-Lung, Su-Ao and Tai-Chung ports were surveyed. The results of field investigations are analyzed and will provide a reference to port authority for corrosion prevention and maintenance strategy in the near future. Results indicated that corrosion rate of steel piles without corrosion prevention at No.5 & 6 wharfs in Hwa-Liang port is less than 0.1 mm/yr (far less than designed criteria value). However, Hwa-Liang port has been constructed over 30 years, parts of steel sheet-piles thickness are reduced over 3.0 mm and almost reach to the maximum allowable deduction value. It would make piles structures deficient in force-bearing. As to Kee-Lung, Su-Ao and Tai-Chung ports, Steel piles with cathodic protection are well prevented from corrosion; and wharfs are in good situations.