Objective To study the mechanisms of levofloxacin,thymopentin combined with decoction of four noble drugs for treatment of patients with severe pulmonary tuberculosis and offer a new therapeutic strategy for treatment of the disease.Methods A total of 100 patients with severe pulmonary tuberculosis admitted to Qinghai Fourth People's Hospital from November 2013 to January 2016 were enrolled,and they were divided into a research group (50 patients) and a control group (50 patients) by random number table.The patients in two groups were treated with 2HRZE/4HR standardized therapy program.The patients in the research group were additionally treated with levofloxacin (0.5 g orally taken,1 times a day),thymopentin (1 mg intravenous injection,once a day) combined with decoction of four noble drugs (ginseng 9 g,poria 9 g,atractylodes 9 g,and licorice 6 g,all the above ingredients were immersed in 400 mL water and boiled to 100 mL,one dose orally taken daily and it was equally divided into 2 parts,one part taken in the morning and the remaining part taken in the evening).Four months after treatment,the changes of indexes of immune functions [total lymphocyte count (LY),CD4+,CD8+,and CD4+/CD8+ ratio],blood coagulation indexes [prothrombin time (PT),activated partial thromboplastin time (APTT),thrombin time (TT),D-dimer,and plasma fibrinogen (Fib)],pulmonary function indexes [forced vital capacity (FVC),peak expiratory flow rate (PEF),forced expiratory maximum volume in 1 second (FEV1),and mean maximum expiratory flow (MMEF)] and blood gas analysis indexes [arterial partial pressure of carbon dioxide (PaCO2),arterial partial pressure of oxygen (PaO2),pulse oxygen saturation (SpO2),and oxygenation index (PaO2/FiO2)] and the therapeutic effects were observed in the two groups.Results After treatment,the CD8+,TT,PT,Fib,D-Dimer and PaCO2 of two groups were decreased significantly than those before treatment (all P ＜ 0.05);while the LY,CD4+,CD4+/CD8+ ratio,FEV1,FVC,PEF,MMEF,APTT,PaO2,SpO2 and PaO2/FiO2 of two groups were all increased significantly than those before treatment (all P ＜ 0.05).The changes of the study group were more obvious than those of the control group [LY (109/L):1.79 ± 0.19 vs.1.45 ± 0.16,CD4+:0.40 ± 0.03 vs.0.33 ± 0.03,CD8+:0.20 ± 0.01 vs.0.23 ± 0.02,CD4+/CD8+ ratio:2.10 ± 0.23 vs.1.67 ± 0.20,FEV1:0.269 ± 0.004 vs.0.198 ± 0.003,FVC:(3.78 ± 0.41)％ vs.(3.14 ± 0.39)％,PEF (L/s):3.68 ± 0.26 vs.3.05 ± 0.23,MMEF (L/s):0.96 ± 0.06 vs.0.74 ± 0.05,PaO2 (mmHg,1 mmHg =0.133 kPa):95.11 ± 7.68 vs.85.23 ± 7.01,PaCO2 (mmHg):31.76± 3.26 vs.46.28±4.36,SpO2:0.96±0.08 vs.0.91 ±0.07,PaO2/FiO2 (mmHg):310.58± 11.12 vs.285.01 ± 10.76,TT (s):15.64± 1.25 vs.18.82 ± 1.54,PT (s):12.69 ± 1.01 vs.14.28 ± 1.21,APTT (s):29.01 ± 2.02 vs.25.21 ± 1.80,Fib (mg/L):233.46 ± 15.61 vs.286.27 ± 18.14,D-Dimer (μg/L):210.88 ± 14.13 vs.256.39 ± 16.47,all P ＜ 0.05].After combined treatment,the sputum negative conversion rate [94％ (47/50) vs.60％ (30/50)],the total efficiency [88％ (44/50) vs.64％ (32/50)] and the focus absorption rate [86％ (43/50) vs.60％ (30/50)] of research group were significantly higher than those of the control group (all P ＜ 0.05).Conclusions The combination of levofloxacin,thymopentin and decoction of four noble drugs on the bases of 2HRZE/4HR standardized therapy for treatment of patients with severe pulmonayr tuberculosis can help to regulate acid-base balance,improve the hypoxia condition and lung function,elevate the immune function and increase the blood circulation in the body to improve clinical efficacy.