Abstract: Objective To study the changes of laboratory test indexes of pneumonia patients infected by novel coronavirus and its clinical significance to provide scientific reference for clinical diagnosis and treatment. Methods The relevant blood test indexes of 80 patients with new diagnosed novel coronavirus pneumonia admitted to our hospital in 2020 were retrospectively analyzed. Normal physical examination subjects were enrolled as Group A （n=40 cases）, patients with pneumonia suspected of novel coronavirus infection were Group B （n=40 cases） and patients with pneumonia diagnosed as novel coronavirus infection were Group C（n=80 cases）. The changes of laboratory blood routine, T lymphocyte subgroup and biochemical parameters in the three groups were compared. Results Compared with normal group A, WBC, L（%）, RBC, HGB, CD3⁺, CD4⁺, CD8⁺, BUN, UA, in confirmed group C were lower than those in normal group A, with statistical difference（P<0.05）;while G（%）, hs-CRP, ALT, AST, TB, DB, SAA, LDH, CK-MB in confirmed group C were higher than those in normal group A, with statistical difference（P<0.05）.Compared with suspected group B, CD4⁺、TnI are lower in confirmed group C than that in suspected group B, AST, SAA, LDH, CK-MB in confirmed group C are higher than those in suspected group B with statistical difference（P<0.05）. There was no significant difference in PLT, CD4⁺/CD8⁺, CR, CYC, PCT, MYO, CK among the three groups（P>0.05）. Multivariate logistic stepwise regression analysis showed that the higher are in SAA, CK-MB, LDH, AST\TB, DB, the greater is the risk of novel coronavirus pneumonia; The lower are in the WBC, L%, HGB, BUN, UA, CD4⁺, CD8⁺, the greater is the risk of novel coronavirus pneumonia. Conclusion The changes of various laboratory indexes in patients infected by novel coronavirus have obvious significance. These indexes have certain reference value for the early diagnosis and treatment of novel coronavirus.It is an effective supplement to nucleic acid test（a gold standard method）, which is helpful for clinical diagnosis of novel coronavirus pneumonia.

Key words: SARS-CoV-2, COVID-19, Laboratory, indicators