Abstract: Objective 　To observe the effect s of Diyushengbai tablet (DY) on leucocyte decreasing in chemotherrpy of non-small cell lung cancer (NSCLC) . Methods 　42 patients of NSCLC were randomized into two groups : observational group (21 patients, PC + DY), control group (19 patients, PC only) . To investigate the medullary inhibition lever and the quantity of colony stimulating factor being used. Results The rate of Ⅲand Ⅳmedullary inhibition was 29. 0 % in observational group was significant lower than in cont rol group of 62. 0 %( P < 0. 05) . The colony stimulating factor could turn the down leucocyt up to snuff ( > 4 ×109 / L) . It took average 3. 5and 5 days in observational group and cont rol group respectively. The quantity of colony stimulating factor (150μg) being used in observational group and cont rol group were 0. 58 ±1. 99 and 1. 93 ±3. 62 respectively and it had a significant difference with P < 0. 05. Conclusion 　DY is better in the chemotherapy of NSCLC by decerasing the medullary inhibition, improving the down leucocyt and reducing the risk of chemotherapy. DY has a better effect and low price and can be used together with colony stimulating factor in clinic.