Objective：To explore the differentiating value of linear circular enhancement on abscess and primary necrotic tumor. Methods：CT imaging data of 112 patients and relevant pathological images of 93 patients with abscess and primary necrotic tumor confirmed by pathology，operation or clinical following-up from January 2016 to October 2018 were retrospectively analyzed. Occurrences of linear circular enhancement in two kinds of diseases were counted and the result was analyzed by using the chi-square test. Results：Among 73 patients with abscess and 39 patients with primary necrotic tumor，65 and 2 had linear circular enhancement，with percentage of 89.0% and 5.1%，respectively. Among 8 patients with misdiagnosed abscess，7（87.5%） had this sign，while 3 misdiagnosed cases of primary necrotic tumor had no sign，with significant differences between abscess and primary necrotic tumor（P<0.05）. Furthermore，pathological images showed that major inflammatory granulation tissue wrapped around the necrotic area in abscess，containing many capillaries；the edge of necrosis area in tumor was tumor cells，disorderly and few nourishing vessels. Conclusion：Manifestation of lin－ear circular enhancement as inflammatory granulation tissue in enhanced CT images can an iconographical differentiating index for both abscess and primary necrotic tumor.