Abstract: Density functional theory with B3LYP functionals was used to study generating phenanthrene derivatives mechanism of acetylenic-keton intramolecular cyclization reaction catalyzed by AuCl₃. It shows that the reaction can occur through 2+2 and 2+6 reaction pathways with and without AuCl₃ catalyst. Without catalyst, energy barrier of rate determining step of 2+2 pathway is lower than that of 2+6 pathway by 32.01 kJ·mol^-1. Reaction mainly occurs through 2+2 pathway. With AuCl₃ catalyst, dominent reaction pathway is still 2+2 pathway with an energy barrier of rate determining step of 137.05 kJ·mol^-1. Energy barrier of rate determining step of four-membered ring pathway with AuCl₃ catalyst is 102.72 kJ·mol^-1 lower than that of reaction without catalyst. This difference indicates that AuCl₃ is an efficient catalyst which can raise reaction rate and moderate reaction condition.