Objective:To evaluate the diagnostic value of hydrogen sulfide breath test(SBT) for small intestinal bacterial overgrowth (SIBO).Methods:College students were enrolled to complete gastrointestinal symptom scale, food frequency questionnaire, lactulose hydrogen- methane breath test (LHMBT) and SBT. Based on the correlation between hydrogen sulfide(H 2S) and hydrogen or methane gas,the receiver operating characteristic (ROC) curve of H 2S was drawn and diagnostic criteria of SBT was defined. Results:A total of 300 subjects including 84 males and 216 females with age 17-32 (21.6±2.4) years were enrolled from April 2019 to December 2019 and divided into two groups.Two hundred and three patients reported SIBO discomforts with 99 (48.8%) LHMBT positive, while 38 (39.2%) were LHMBT positive in 97 health controls. Rise of H 2S at 90 min was positively related with that of hydrogen ( r=0.516, P<0.01), and H 2S levels at 90 min were positively correlated with methane ( r=0.632, P<0.01). A rise in H 2S of ≥25.0 ppb or H 2S levels ≥62.5 ppb at 90 min during lactulose breath test was considered positive for SIBO, that sensitivity, specificity and accuracy were 66.4%,79.1% and 73.3% respectively. H 2S levels were significantly related to the amount of Vitamin B 12 intake ( P=0.011). H 2S-positive subjects exhibited a constipation-predominant pattern. Conclusion:SBT is consistent with LHMBT, especially in constipation-predominant patients, which may provide a reference to the diagnosis of SIBO.