〔Abstract〕 Objective To explore the causal association between gut microbes and non-alcoholic fatty liver disease(NAFLD) by Mendelian randomisation analysis. Methods Genetic instrumental variables for gut microbiota were identified from a gene-wide association study of 18 340 participants, and summary statistics for NAFLD were obtained from the FinnGen database, which provided data on 894 NAFLD cases and 217 898 controls using the IVW method as the primary analysis. In order to test the robustness of the results, MR-Egger method, WM method, Simple Mode method, Weighted Mode method were used for Mendelian randomisation analysis, and heterogeneity test, sensitivity analysis, and multiplicity analysis were performed. Results class Gammaproteobacteria IVW results showed(OR=0.621, 95%CI=0.412～0.934,P=0.022); family Enterobacteriaceae IVW results showed(OR=1.481, 95%CI=1.069～2.053,P=0.018);genus Lachnospiraceae IVW results showed(OR=1.405, 95%CI=1.036～1.904,P=0.029); genus Prevotella7 IVW results showed(OR=0.834, 95%CI=0.714～0.974,P=0.021); genus Prevotella9 IVW results showed(OR=1.251, 95%CI=1.025～1.527,P=0.027); order Desulfovibrionales IVW results showed(OR=0.714, 95%CI=0.519～0.982,P=0.038); order Enterobacteriales IVW results showed(OR=1.481, 95%CI=1.069～2.053,P=0.018). And there was no heterogeneity in the heterogeneity test, and the sensitivity analyses all showed robustness and no pleiotropy was found. Conclusion This study implicates class Gammaproteobacteria, family Enterobacteriaceae, genus Lachnospiraceae, genus Prevotella7, genus Prevotella9, order Desulfovibrionales, order Enterobacteriales seven species of gut microorganisms have a causal relationship with NAFLD.