To investigate the risk factors and short-term prognosis of early pulmonary hypertension (PH) in preterm infants. A retrospective case-control study was performed in preterm infants (gestational age <32 weeks) in the neonatal intensive care unit (NICU) of the Children's Hospital, Zhejiang University School of Medicine from January 2012 to December 2019. Eighty preterm infants with a diagnosis of PH between 3 and 14 days (early PH group) were matched in gestational age and sex with the controls (1∶2) of the same period in NICU. Perinatal clinical records, complications, echocardiography and early outcomes were collected. Characteristics and outcomes were compared between the two groups with -test, nonparametric test or Chi-square test. Multivariate Logistic regression was used to analyze the predictive factors of early PH. The gestational age of the early PH group and the control group were both (27.9±1.4) weeks, and 52 (65.0%) and 104 (65.0%) were males in each group, respectively. Univariate analysis showed that birth weights were lower in the early PH group than those in the control group (1 030 (850, 1 200) 1 110 (1 000, 1 278) g, -3.27, 0.001). The early PH group had higher rates of pregnancy-induced hypertension, prolonged rupture of membranes (PROM) >1 week, born by caesarean, small for gestational age (SGA), 1 and 5 min Apgar score ≤7 scores, neonatal respiratory distress syndrome (RDS) and hemodynamic significant patent ductus arteriosus (hsPDA) (12.5% (10/80) 3.8% (6/160), 11.2% (9/80) 3.8% (6/160), 48.8% (39/80) 28.8% (46/160), 10.0% (8/80) 1.9% (3/160), 70.8% (51/72) 51.7% (74/143), 50.0% (36/72) 20.3% (29/143), 88.8% (71/80) 59.4% (95/160), 85.0% (68/80) 22.5% (36/160), χ6.56, 5.12, 3.31, 8.05, 7.17, 20.05, 21.58, 84.84, all <0.05). Multivariate Logistic regression analysis showed that the independent predictive factors of early PH were PROM >1 week, SGA, 5 min Apgar score ≤7 scores, nenonatal RDS and hsPDA (10.40, 18.61, 4.47, 4.13, 20.10, 95% 1.93-56.12, 2.82-122.76, 1.91-10.46, 1.50-11.39, 8.28-48.80, all <0.05),respectively. Infants with early PH had higher incidence of bronchopulmonary dysplasia (BPD), BPD associated PH, severe intraventricular hemorrhage (IVH), extrauterine growth retardation (EUGR), laser treatment for retinopathy of prematurity (ROP) and mortality than the controls (all 0.05). The duration of invasive mechanical ventilation was also longer in the early PH group than that in the control group (0.05). Risk of early PH will be increased in preterm infants with PROM >1 week, SGA, 5 min Apgar score ≤7 scores, and comorbidities of nenonatal RDS and hsPDA. Early PH is associated with increased mortality, BPD, BPD associated PH, severe IVH, EUGR and laser treatment for ROP.