OBJECTIVE To study the clinical features and prognosis of preterm infants with varying degrees of bronchopulmonary dysplasia (BPD). METHODS The clinical data of 144 preterm infants with a gestational age of <32 weeks who were admitted to the neonatal intensive care unit from March 2014 to March 2016 and were diagnosed with BPD were collected. According to the severity of BPD, these preterm infants were divided into mild group with 81 infants and moderate/severe group with 63 infants. The two groups were compared in terms of perinatal risk factors, treatment, comorbidities, complications, and prognosis of the respiratory system. RESULTS Compared with the mild BPD group, the moderate/severe BPD group had a significantly higher gestational age and rate of small-for-gestational-age (SGA) infants (P&lt;0.05), as well as a significantly higher rate of severe preeclampsia and a significantly lower rate of threatened preterm labor (P&lt;0.05). Compared with the mild BPD group, the moderate/severe BPD group had a significantly higher percentage of infants who needed mechanical ventilation at 2 weeks after birth, longer duration of mechanical ventilation, total time of oxygen therapy, and length of hospital stay, and higher incidence rates of pneumonia and cholestasis (P&lt;0.05), as well as a significantly lower application rate of caffeine citrate (P&lt;0.05). The multivariate logistic regression analysis showed that SGA birth (OR=5.974, P&lt;0.05), pneumonia (OR=2.590, P&lt;0.05), and mechanical ventilation required at 2 weeks after birth (OR=4.632, P&lt;0.05) were risk factors for increased severity of BPD. The pulmonary function test performed at the corrected gestational age of 40 weeks showed that compared with the mild BPD group, the moderate/severe BPD group had significantly lower ratio of time to peak tidal expiratory flow to total expiratory time, ratio of volume to peak tidal expiratory flow to total expiratory volume, and tidal expiratory flow at 25% remaining expiration (P&lt;0.05). The infants were followed up to the corrected gestational age of 1 year, and the moderate/severe BPD group had significantly higher incidence rates of recurrent hospital admission for pneumonia and recurrent wheezing (P&lt;0.05). CONCLUSIONS SGA birth, pneumonia, and prolonged mechanical ventilation are associated with increased severity of BPD. Infants with moderate or severe BPD have poor pulmonary function and may experience recurrent infection and wheezing.