A synthesis method of an indole derivative capable of efficiently degrading a perfluorinated compound (PFC) and a use of the indole derivative are provided. The synthesis method includes dissolving an appropriate amount of indole, alkylamine, and formaldehyde in an ethanol solution, conducting a reaction at reflux under suitable conditions for a specified period of time with ZnCl2 or glacial acetic acid as a catalyst to form a reaction product, vacuum-drying the reaction product, and purifying the reaction product through column chromatography to obtain a novel indole derivative with a hydrophobic alkyl branch. The present indole derivative has some hydrophobicity and a positively charged amino group that can effectively capture PFCs in contaminated water to produce a sub-nanoscale self-assembled aggregate. Hydrated electrons generated by light irradiation can directly attack PFCs in the aggregate without long-distance mass transfer, improving the utilization rate of hydrated electrons and reduces the ratio of fed materials.