Objective： To analyze the role of anti-collectin 11 in the diagnosis of systemic lupus erythematosus (SLE) and in the evaluation of disease activity. Methods: This was a cross-sectional study. Five groups of patients were enrolled: SLE active (SLE disease activity index-2000，SLEDAI-2000≥9), SLE remission (SLEDAI-2000≤4 and there was no organ involvement), rheumatoid arthritis (RA), primary Sj-gren Syndrome (SS) and healthy control (HC). Serum anticollectin 11 was detected in all the groups by ELISA. One-way ANOVA analysis and LSD-t test as post-hoc analysis were used to compare the levels of anticollectin 11 among all the groups. Receiver operating characteristic (ROC) curve and the area under curve (AUC) were used to analyze the value of anticollectin 11 in the diagnosis of SLE. Results: In the study, 30 patients were enrolled in each group, including 13 males and 137 females with an average age of (34±14) years (18-77 years). The age and gender of the other three groups were comparable to the two SLE groups. The difference of serum anti-collectin 11 between the SLE active group and SLE remission group was not statistically significant (88.8±16.8 vs. 89.7±24.7, P=0.896). The level of serum anti-collectin 11 was significantly higher in SLE group (as a whole) (89.1±19.4) than in RA group (49.1±22.0), SS group (56.9±30.1) and HC group (72.7±24.6) (P＜0.001, P＜0.001, P=0.007, respectively). The AUC was 0.806 for the diagnosis of SLE by serum anti-collectin 11. Further descriptive analysis showed that the positive rate of anti-collectin 11 was very high in the patients of SLE in whom both anti-double-stranded DNA (dsDNA) and Sm antibody were negative. The nervous system and gastrointestinal system involvement were the most common in the patients with positive anti-collectin 11. Conclusion: The level of serum anti-collectin 11 was significantly higher in SLE than in RA, SS and HC. Anti-collectin 11 antibody had a relatively high value in the diagnosis of SLE and it might have some complementary function in the diagnosis of SLE. It might be a relatively specific autoantibody for SLE.