The invention discloses a method for modifying a catalyst carrier by ultraviolet radiation. The method comprises the following steps: mixing catalyst carrier activated carbon with modified gas in ultraviolet light radiation environment in a reactor; performing ultraviolet light modification reaction; then removing residual gases to obtain an activated carbon carrier with a high content of functional groups. The method can realize rapid modification of carriers of chlorine, nitrogen and other functional groups, has modification speed higher than that of conventional acid treatment, roasting and other modification methods for activated carbon, has high content of modified functional groups, apparently improves activity or stability of an acetylene hydrochlorination catalyst, and is low in pollution to environment and simple in modification process.