Pretreatment is the key step in carbon curing system, which is very important for cement paste carbonization. In this study, the cement specimens before carbonation were pretreated by ultraviolet (UV) irradiation and compared with standard pretreatment, and the carbonation depth, compressive strength, CO2 absorption and structural morphological changes of hydration products were tested and analyzed. The results show that the mass loss of cement specimens after UV pretreatment is 5.3 times as standard curing pretreatment. After accelerated carbonization, the carbonization depth increases by 2.4 times, the mass increases by 4.5 times, the early compressive strength increases by 18.9%, and the CO2 absorption increases by 0.25%. It is found that UV pretreatment increases the formation of silica gel (Q3+Q4) content with high degree of polymerization of carbonized cement specimens. Therefore, UV pretreatment can significantly accelerate the water loss and decalcification of the specimen, which has a significant enhancement effect on the carbonization process of cement specimens.