Abstract: Gut microbiota, the largest microbial community in the body, plays an important role in maintaining the immune homeostasis of the intestinal system and even the extraintestinal organs. Recently, increasing evidence has highlighted the substantial impact of gut microbiota on the cancer progression and therapy. Intervention of gut microbiota is considered as a promising anti-tumor strategy. Though the molecular mechanisms remain mostly unknown, it is widely appreciated that microbiota-derived metabolites critically mediate the interplay between host and microbiota, triggering enthusiasm to understand the mechanism behind. This article summarizes the latest progress in understanding mechanisms of microbial metabolites in regulating host immune responses, in particular in antitumor immunity. With this, we hope to provide insights for new therapeutics from the perspective of microbiota intervention.