Abstract: OBJECTIVE To analyze the diagnostic values of serum calcitonin gene related peptide（CGRP）, matrix metalloproteinase（MMP）-9 and procalcitonin（PCT） in stroke patients complicated with pulmonary infection. METHODS A total of 128 stroke patients who were treated by neurology department of the First Affiliated Hospital of Hainan Medical College from Jan 2019 to Dec 2020 were selected as the study subjects, and were divided into the 72 cases of infection group and 56 cases of the non-infection group according to whether pulmonary infection occurred. The infection-related factors, immune function indexes, serum CGRP, MMP-9 and PCT levels at admission between the two groups of patients were compared. RESULTS The age, the proportion of diabetes mellitus, the proportion of chronic obstructive pulmonary disease and the National Institute of Health Stroke Scale（NIHSS） score of the patients in the infection group were significantly higher than those in the non-infection group（P＜0.05）. The percentage of peripheral blood CD₄⁺ T lymphocytes, the ratio of CD₄⁺/CD₈⁺ T lymphocytes and the serum IgG, CGRP levels of the patients in the infection group were significantly lower than those of the non-infection group（P＜0.05）, the serum MMP-9 and PCT levels were significantly higher than those in the non-infection group（P＜0.05）. The areas under receiver operating characteristic curve（AUC） of serum CGRP, MMP-9 and PCT in diagnosis of stroke complicated with pulmonary infection were 0.788, 0.654 and 0.752（P＜0.05）, respectively, among which, the diagnostic sensitivity of CGRP was the highest, which was 0.903, the diagnostic specificity of PCT was the highest, which was 0.892. When the three were tested in combination, AUC was increased to 0.890（P＜0.05）. CONCLUSION The incidence of stroke complicated with pulmonary infection was related to many factors, and the immune function damages of the patients were more significant. The serum CGRP, MMP-9 and PCT levels in early admission to hospital had auxiliary diagnostic values for pulmonary infections, and the combined detection of the three indexes could improve the diagnosis efficiency.