Obejective: To investigate the effects of different doses of protein diet on nutritional status, immune function and oxidative stress in patients with type 2 diabetes mellitus (T2DM) with pulmonary tuberculosis. Methods: 120 T2DM patients with pulmonary tuberculosis who were admitted to Hunan Provincial Chest Hospital from March 2020 to December 2021 were selected as research objects. Patients were randomly divided into high protein group (1.5 g/kg/d protein, total calorie increased by 10%), medium protein group (1.2 g/kg/d protein, total calorie increased by 10%), low protein group (1.0 g/kg/d protein, total calorie increased by 10%). 40 cases in each group. The sputum mycobacterium tuberculosis negative conversion, pulmonary infection, blood glucose, nutritional status, immune function and oxidative stress level in three groups were compared. Results: The sputum mycobacterium tuberculosis negative conversion rate in high protein group and medium protein group was higher than that in low protein group, and high protein group was higher than that of medium protein group (P<0.05). The pulmonary infection rate in high protein group and medium protein group was lower than that in low protein group, and high protein group was lower than that of medium protein group (P<0.05). After treatment, the glycosylated hemoglobin (HbA1c), fasting blood glucose (FBG) and 2h postprandial blood glucose (2hPG) in high protein group and medium protein group were lower than those in low protein group, and high protein group was lower than that of medium protein group (P<0.05). After treatment, total albumin (TP), prealbumin (PA) and albumin (ALB) in high protein group and medium protein group were higher than those in low protein group, and high protein group was higher than that of medium protein group (P<0. 05). After treatment, CD3+, CD4+ and CD4+ /CD8+ in high protein group and medium protein group were higher than those in low protein group, and high protein group was higher than that of medium protein group (P<0.05). After treatment, CD8+ in high protein group and medium protein group was lower than that in low protein group, and high protein group was lower than that of medium protein group (P<0.05). After treatment, the superoxide dismutase (SOD) in high protein group and medium protein group was higher than that in low protein group, and high protein group was higher than that of medium protein group (P<0.05). After treatment, the malondialdehyde (MDA) in high protein group and medium protein group was lower than that in low protein group, and high protein group was lower than that of medium protein group (P<0.05). Conclusion: High protein diet can improve the nutritional status and immune function of T2DM patients with pulmonary tuberculosis, and reduce the level of oxidative stress. [ABSTRACT FROM AUTHOR]