Fouling in shell and tube heat exchangers can result in low heat transfer efficiency due to the increase of heat resistance, large pump energy consumption from the high pressure drop in the shell side or tube side. This paper summarizes the fouling mechanism and cleaning technology of shell and tube heat exchanger. Fouling can be affected by fluid velocity, fluid composition, fluid flow state, and the structure of the shell and tube. Fouling can be reduced by using surface and fluid treatments, and removed by cleaning technologies, including high pressure water jet, mechanical and chemical approaches. Design of shell and tube heat exchanger can be improved to avoid fouling by adjusting the shell and tube structure, arranging the fluid flow sides, controlling the fluid velocity, and changing the temperature distribution of the shell and tube.