Disclosed is a manufacturing method of 1,2-dichlorohexafluorocyclopentene. The first reaction uses dicyclopentadiene as a starting material and nitrogen gas or another inert gas as a diluting agent in a gas-phase thermal cracking reaction to obtain cyclopentadiene. The second reaction uses cyclopentadiene as a starting material in a liquid phase chlorination reaction with chlorine gas to obtain 1,2,3,4-tetrachlorocyclopentane. The third reaction uses 1,2,3,4-tetrachlorocyclopentane as a starting material in a gas-phase chlorination and fluorination reaction with hydrogen fluoride and chlorine gas in the presence of a chromium-based catalyst to obtain 1,2-dichlorohexafluorocyclopentene. The method uses easily acquired starting material and a stable fluorination catalyst, provides a high yield for a target product, and is applicable for large-scale continuous gas-phase production of 1,2-dichlorohexafluorocyclopentene.