Abstract: Chronic obstructive pulmonary disease and asthma are complex inflammatory diseases with airway obstruction as the main characteristics, and have become common respiratory diseases that seriously affect human health. Compared with the clinical use of PDE3 or PDE4 inhibitors alone, dual PDE3/4 inhibitors have synergistic anti-inflammatory and bronchodilator effects, and have attracted widespread attention in recent years. This article reviews the representative research results of dual PDE3/4 inhibitors currently in the preclinical and clinical research stages, summarizing their latest progress and their potential for the treatment of chronic obstructive pulmonary disease and asthma.