The deep curing of UV ink is different, and it has huge effects on the performance of thick ink film. Initiator which is one of important components of UV ink has a greater impact on the curing of ink. It has great help to the deep curing of UV ink by choosing the correct initiator to make UV ink. In order to increase the curing rate of printing thick ink film with UV ink, other components of UV ink were fixed, and the variety and content of initiators were changed to make ink. By printing proofing in different ink thickness, the ink double bonds converted of proofs which were in different ink thickness were tested, and the relationship between the variety and content of initiators and the curing rate of different ink thickness. To make the ink with different kinds of composite initiators, the variety and content of initiators which had higher curing rate at thick ink film were obtained. The results show that After mixing prepolymers 6325-100 and monomer in certain proportion, the ink with light initiator ITX has higher double bond conversion rate than the ink with light initiator TPO or BP; the ink with light initiator TPO or ITX, when the ink layer is thin, the double bond conversion rate increased with the increase of the thickness, when the ink layer is thick, the double bond conversion rate decreased, the ink with light initiator BP, the double bond conversion rate increased with the increase of the thickness. The double bond conversion rate of the UV ink increased with the increase of UV light power. When the ink layer is thin, content of light initiator ITX at 8%, the double bond conversion rate is the highest; when the ink layer at the thickness 40um, content of light initiator ITX at 10%, the double bond conversion rate is the highest.