More studies have revealed the pathophysiological mechanisms and treatment of motor symptoms in Parkinson's disease (PD), but the mechanisms and medications for non-motor symptoms (NMS) are more limited, and most patients develop unattended NMS long before diagnosis. In recent years, domestic and international studies have identified a strong link between 5-hydroxytryptamine (5-HT) and PD-NMS and the medication used to treat it. In this paper, we review the current relationship between NMS and 5-HT and its therapeutic use.