Objective To explore, the effect of different dosage of pulmonary surfactant (PS) on the inci-dence of bronchopulmanary dysplasia. Method Four hundred and three premature infants with hyaline membrane disease were divided into 3 groups according to the dose of PS: low-dose group (L-PS group, ≤ 100 mg/kg, n =188) ,high-dose group(H-PS group, > 100 mg/kg, n = 94) and no-PS group (N-PS group, n = 121). The frac-tional inspired oxygen(FiO2) and ptlmonary oxygenating function before and after 6 hours treatment were observed and the durations of oxygen therapy and mechanical ventilation, frequency of repeated intubafion, length of hospi-talization and the incidence of BPD were compared among the three groups. Results After 6 hours PS administra-tion, the FiO2,oxygen index and duration of oxygen therapy and mechanical ventilation were significantly decreased (P <0.05), while PO2 and the arterio-alveolar partial pressure of oxygen were significantly increased (P <0.05)in the H-PS and L-PS groups, compared with the N-PS group. Compared with the L-PS and N-PS groups,the H-PS group showed a decreased incidence of BPD. Conclusions PS administration could improve the pul-monary oxygenation and prevent the development of BPD, especially in high-dose. Key words: Surfactant; Hyaline membrane disease; Bronchopulmonary dysplasia; Infant, Premature