Previous meta-analyses suggested that Chinese herbal medicine (CHM) is effective for irritable bowel syndrome (IBS). Formulas with and as the core pairs have been widely used by traditional Chinese medicine (TCM) practitioners for the treatment of IBS. We aimed to examine the efficacy and safety of the - class formula (A-P CHM) for IBS through a meta-analysis and trial-sequential analysis (TSA). The protocol is registered in the International Prospective Register of Systematic Reviews (PROSPERO) under registration number CRD42023439087. We searched seven databases for data up to May 23, 2023. The primary outcome was global IBS symptom relief. The secondary outcomes included the IBS severity scoring system (IBS-SSS) score and treatment-related adverse events. The relative ratio (RR) (dichotomous variables), the standardized mean difference (SMD) (continuous variables), the number needed to treat (NNT), the number needed to harm (NNH), and the required information size (RIS) were calculated. Twenty-four eligible articles with 3,768 participants were included. Thirteen trials were at low risk of bias (RoB). Compared with placebo or Western medication, A-P CHM was associated with a significantly higher proportion of relief of global IBS symptoms. The TSA analysis verified the primary outcome. For the secondary outcome, the A-P CHM IBS-SSS score was lower than Western medication or placebo at the end of the treatment, which was further confirmed by the TSA analysis. We asserted that A-P CHM might be a potential candidate for patients with IBS, especially for IBS-D. It may provide a theoretical basis for future optimization of irritable bowel syndrome with diarrhea (IBS-D) herbal formulas. The overall certainty of the evidence was not high; more tightly designed randomized controlled trials (RCTs) are required in the future.