Observational studies have reported that dysbiosis of gut microbiota may be a contributing factor in the development of IBD. However, the causal relationship between gut microbiota and IBD remains unclear due to the coexistence of gut dysbiosis in IBD patients. The aim of this study is to investigate the causal and reverse causal relationships between gut microbiota and inflammatory bowel disease (IBD).We aimed to explore the causal and reverse causal relationships between gut microbiota and IBD using a two-sample Mendelian randomization (MR) approach. Specifically, genetic variants associated with IBD were selected from the International IBD Genetics Consortium (IIBDGC) trans-ancestry genome-wide association studies (GWAS), while data related to gut microbiota were obtained from the International MiBioGen consortium. We employed various MR methods, including inverse variance-weighted (IVW), MR-Egger regression, weighted median, weighted mode, and MR-RAPS. Sensitivity analyses using MR-Egger intercept test, Cochran's Q test, and leave-one-out test were conducted for quality control.As results, Bifidobacteriaceae, Bifidobacterium, Lactobacillaceae, Lachnospiraceae UCG008 and Paraprevotella reduce the risk of CD. Family XIII AD3011 reduces the risk of CD and UC. Clostridiales vadin BB60 group reduces the risk of UC. Lachnospiraceae UCG010 genus, Oxalobacteraceae, Oxalobacter and Intestinimonas promotes CD development. Paraprevotella, Eubacterium ruminantium and Prevotellaceae genus promotes UC development. Eubacterium coprostanoligenes, Ruminococcaceae UCG005 genus promotes CD and UC development.Based on Cochran's Q test and MR-Egger intercept, there is no evidence of potential heterogeneity or pleiotropy bias in our findings. In conclusion, this study suggests that the use of novel probiotics for adjunctive therapy in IBD may present a new avenue for future IBD treatment.