COPD often coexists with other diseases, which have an important impact on COPD condition and prognosis. The risk of comorbidity is also a risk factor for exacerbation of COPD symptoms. 1. Cardiovascular disease is the most important comorbidity and the leading cause of death in COPD patients. COPD patients with comorbid cardiovascular disease have a higher mortality rate than those without comorbid cardiovascular disease. 2. Osteoporosis is the main comorbidity of COPD and is often underdiagnosed. Studies have shown that osteoporosis can be present in the early stages of COPD. 3, Cancer is common in COPD patients and is the most common cause of death in mild COPD patients. 4, COPD patients with nasal symptoms or nasal inflammatory disease correlates with exacerbation and worsening of the disease. 5, COPD patients often have acute and chronic lower respiratory tract infections. 6.OPD is complicated by pulmonary hypertension. 7, AECOPD is often combined with venous thromboembolic disease. In severe AECOPD patients with refractory hypoxemia, the possibility of pulmonary embolism should be considered. 8.Clinically, COPD patients with emphysema are often combined with pulmonary fibrosis, and the incidence of pulmonary hypertension is higher in these patients with relatively normal lung volume and significantly reduced diffusion capacity. 9, COPD patients commonly have skeletal muscle weakness, which can precede cachexia. Studies have shown that skeletal muscle atrophy is evident in patients with advanced COPD and is associated with increased respiratory function, activity tolerance, health status, and mortality. Systemic inflammation is an important cause of weight loss and muscle atrophy in COPD patients. 10, Depression is also a common comorbidity, suggesting a poor prognosis.