Cooling pipe made of 20^# seamless tube is widely used to cool liquid zinc in zinc smelting industry. Since its life is especially short, the consumption of cooling pipe is very high. By using finite element analysis method, the thermal stress distribution is obtained and the site of the maximum thermal stress lies in the joint of bent section and straight section and inclines to the bent section. The residual stress is measured by using the cut method. Liquid zinc has low surface tension and high permeability and corrosivity. It can form Fe~ Zn alloy with steel in the cooling pipe and can dissolve C and Si in cooling pipe. Liquid zinc is not compatible with cooling pipe. Therefore, the compatibility is a decisive factor on the life of cooling pipe in liquid zinc. The damage of the cooling pipe in liquid zinc is caused by high temperature corrosion and stress corrosion. Thermal stress plays an important role between the thermal stress and the residual stress in determine the position of the damaged site of the cooling pipe in liquid zinc.