The Taozhu city wall, built in the Ming dynasty, is the most completely preserved ancient garrison city wall in Zhejiang, and is a key unit of the protected national cultural relics. Investigation of the current status of the wall shows that major types of damage include partial collapse, bloating, and mortar erosion. The internal causes are structural strength defects and the lack of a waterproofing system; the external factors are rain and plant growth. These problems are common in the southeast coastal areas of China. Based on these factors, the characteristics of the wall and a review of protective measures use for other ancient city walls, a preliminary protection plan is presented for the Taozhu city wall. Our investigation can be used as a reference for protective measures at other sites.