Tube hydroforming (THF) is an efficient and economical technology of tube cool-plastic forming process. Loading path is one of the most efficacious factors which affect the THF process and quality of hydroforming parts. The forming failures, such as bursting, buckling and wrinkling, can be avoided by using suitable loading path in the THF process. Furthermore, an optimal loading path is beneficial to improve the uniformity of wall thickness and formability of material. In this paper, the importance of loading path to THF process is briefly discussed; typical optimization methods of loading path are enumerated and classified; characteristics and insufficiencies of these methods are pointed out. Main problems and trends of development in optimization methods are summarized.