An oral composite tablet and a method of preparing the oral composite tablet are provided. The oral composite tablet includes: a sustained-release layer containing melatonin or a pharmaceutically acceptable salt thereof, and a gel-forming polymer as a release-sustaining agent； and a immediate-release layer containing sertraline or a pharmaceutically acceptable salt thereof.本發明提供一種口服複合錠劑和一種製備口服複合錠劑之方法。前述口服複合錠劑包括：持續釋放層，前述持續釋放層含有褪黑激素或其醫藥學上可接受之鹽、和作為釋放維持劑的凝膠形成聚合物；以及立即釋放層，前述立即釋放層含有舍曲林或其醫藥學上可接受之鹽。
