Abstract: <b<Objective</b< Discuss the application of high pressure injector in CT Contrast Enhancement. <b<Methods</b< 2338 patients underwent CT Contrast Enhancement using high pressure injector.300 patients underwent CT Contrast Enhancement by manual injection were also studied as contrast group. All the patients had negative iodin allergy test results before the examination. The inject speed is 2-3ml/s for adult,and it's 0.5-1.5 ml/s for neonates. The dose of contrast media is 50-80ml for adults; and it must be calculated by the weight for neonates. <b<Results</b< In high pressure injector group, 4 cases had severe allergic shock, which occupied 0.17%; 27 cases had moderate reaction, which occupied 1.2%; 56 cases had mild reaction, which occupied 2.4%; and 9 cases were failed to inject, which occupied 0.34%. In manual injection group, 1 case had allergic shock, which occupied 0.17%; 5 cases had mild reaction, which occupied 1.6; and displacement of contrast media didn't happen in any case. <b<Conclusion</b< With the increase of the inject speed of contrast media, the quality of the CT imagine will be improve, but the side effect will be improve too. So the inject speed must be seriously considered according to the age, examination position, and the situation of the patients.