Cationic photoinitiator(SR-1012) with Irgacure651 and Irgacure1700 were mixed, respectively. The influence of the content and composition of the composite photoinitiator on photosensitivity of the hybrid system composed of PU, triethyleneglycol diacrylic ester (TEGDA) and epoxy compound EPON-812 was studied. The results showed that the hybrid system had higher curing rate when using composite photoinitiator composed of Irgacure1700 and SR-1012 than that of Irgacure651 and SR-1012 and value of sensitivity was 2.64mJ/cm,2,. The cooperation of free radical initiator and SR-1012 offered considerable photosensitive properties, such as curing rate, sensitivity and gel yield, when the weight ratio of free radical initiator to SR-1012 was 2:1 and value of sensitivity was 6.28mJ/cm,2,. It was also found that suitable concentration of the composite initiator was 4-6%(wt). UV spectrum showed absorbance of λ at 276nm and 333nm.