The effect of low-FODMAPs diet on irritable bowel syndrome (IBS) in Western China has not been reported. We aimed to investigate the effect of low-FODMAPs diet on IBS patients in the area and whether low-FODMAPs diet-induced alterations of microbiota could be improved through probiotics. IBS patients were randomized to the control group, low-FODMAPs diet group, probiotics group, or combined group. IBS Symptom Severity Score questionnaire (IBS-SSS) and IBS Quality of Life Score questionnaire (IBS-QOL) were completed at baseline, 2 and 4 weeks to evaluate the severity of symptoms. Fresh feces were collected for analyses of gut microbiota and short-chain fatty acids at baseline and 4 weeks after intervention. Seventy-three patients were included in the per protocol analysis. After intervention, there was significant improvement in IBS-SSS in the low-FODMAPs group (37.5%, 44.2%), probiotics group (51.4%, 62.0%), and combined group (34.1%, 40.4%) at both 2 weeks and 4 weeks, compared with the baseline ( < .05). In the low-FODMAPs group, the abundance of several microbiota (, , etc.) was significantly decreased. Furthermore, after the supplementation of probiotics in the combined group, the abundance of Genus_, , , , , , and was significantly increased, which was associated with the improvements of symptoms score in the correlation analysis. Our study confirmed the effectiveness and safety of short-term low-FODMAPs diet in IBS symptoms based on the Chinese diet in Western China. The combination of low-FODMAPs and probiotics plays a beneficial role in gut microbiota in IBS.