The replacement and maintenance of the anticorrosive system which is about to reach the design protection period is the necessary way to ensure the reliability and good technical condition of the structure. Aiming at the replacement and maintenance of the sacrificial anode cathodic protection system for steel pipe piles in the old quay of coastal port，referring to the experience of similar projects and relevant codes and standards，we discuss key difficulties，including replacement and maintenance design procedures，the influence，determination and correction of seawater resistivity，protection area and protection current density calculation，sacrificial anode layout and installation，etc. Then，we put forward solutions to the key technical problems to ensure that the anticorrosive system for steel pipe piles is continuous and effective，and to practical ensure the normal use and safe operation of port facilities.