To investigate the differences of clinic-pathological features among ductal carcinoma in situ (DCIS), ductal carcinoma in situ with micro-invasion (DCIS-MI) and early invasive carcinoma (IDC) in stage T1. From January 2014 to December 2018, 308 cases DCIS, DCIS-MI 92 cases and 111 cases of T1a, 343 cases of T1b, and 1032 cases of T1c were investigated in a retrospective analysis. The population and clinic-pathological characteristics including age, menstrual status, surgical mode, lymph node status and molecular markers were compared in each group. Survival rate of all patients were followed up for 5 years. Compared with DCIS-MI group, the higher breast-conserving rate and lower lymph node metastasis rate in the DCIS group were shown in the DCIS-MI group (P < 0.05). There were no significant differences in tumor diameter, number of tumors, ER, PR, HER2 and Ki67 expression, molecular typing, (P > 0.05). The expression of Ki67 in T1a, T1b and T1c groups increased gradually with elevated grades (P < 0.05). The proportion of HER2-positive patients in DCIS-MI group was significantly higher than that in T1a-b-c (P < 0.05). there were no significant differences in DFS and OS between the 3 groups (P > 0.05). The clinic-pathological features of DCIS-MI are similar to those of DCIS and T1a, but significantly different from T1c.