Lamotrigine is a commonly used antiepileptic drug in clinical practice, with significant interindividual variability in its pharmacokinetics. Plasma concentrations of lamotrigine are easily affected by multiple factors such as concomitant medications, genetic polymorphisms, and physiological or pathological conditions. However, the guidance of existing guidelines on its therapeutic drug monitoring (TDM) is still inadequate, especially lacking detailed recommendations for special populations such as pregnant women and children. To standardize the clinical practice of lamotrigine TDM in China and ensure the medication safety and efficacy for epilepsy patients including special populations, this guideline established a multidisciplinary expert panel in accordance with the WHO Handbook for Guideline Development, selected and confirmed key clinical issues through the Delphi method, and adopted the criteria of the Oxford Centre for Evidence-Based Medicine (OCEBM) for evidence quality grading and recommendation strength grading, with recommended opinions formed after multiple rounds of expert consensus. This guideline formulates recommendations covering key aspects including factors influencing lamotrigine plasma concentrations, TDM indications, monitoring indicators, test samples and detection methods, timing of initial and repeated monitoring, plasma concentration reference ranges, results interpretation, and dose adjustment. It provides comprehensive and standardized evidence-based guidance for healthcare professionals at all levels to support personalized treatment and pharmaceutical care in lamotrigine therapy.