Insufficient energy intake and systematic inflammation lead to malnutrition in patients with chronic obstructive pulmonary disease (COPD). Nutritional supplementation improves the patients'nutritional status by increasing energy intake and providing anti-inflammatory elements，which can relieve the patients' symptoms and delay the disease progression.

Malnutrition is very common in patients with COPD. The main reasons include short intake of energy and systematic inflammation. In our randomized and controlled clinical trial, patients will be divided into two groups: the experimental group and the control group. Patients in the experimental group will be provided nutritional supplements in addition to usual diet every day for three months and patients in the controlled group with usual diet. According to the changes of patients' body composition, anthropometrics, inflammatory markers, lung function, respiratory muscle function, exercise capacity, degree of dyspnea and health related quality of life(HRQL) after intervention，the nutritional status and inflammation status are assessed, which contributes to the prediction of prognosis. The nutritional supplements is a kind of oral liquid composed of proteins, omega-3 fatty acids, carbohydrate, vitamins, which provides about 260 kcal energy per 200ml. The patients from the interventional group need drink the nutritional supplements according to the estimated energy intake and a record should be made everyday. The patients will be followed up regularly by the researcher.

Inclusion Criteria:

Patients from Zhujiang Hospital affiliated from Southern Medical University

Patients aged between 40 and 90 years old

Patients gendered into male or female

Patients with pulmonary function test of FEV1/FVC<70% and FEV1<80% predicted

Patients presenting one or more of the following situations of malnutrition or nutritional risk: BMI <21 kg/m2 (or<23 kg/m2 in patients ≥ 65); unintentional weight loss >10% in the past 6 months; unintentional weight loss >5% in last month; FFMI <15 kg/m2 (women) or <16 kg/m2 (men)

Patients able to answer question

Patient able to eat and drink

Patients who signed informed consent

Exclusion Criteria:

Patients with signs of an airway infection

Patients with malignant disorders

Patients with recent surgery

Patients with gastrointestinal ,cardiovascular diseases,neurological diseases or endocrine disease

Patients with bullae lung

patients treated with oral steroids or immunosuppressors

Patients requiring other nutritional supplements or parenteral nutrition

Patients suffering from acute exacerbation over the previous 4 weeks

Patients with lack of motivation or poor compliance