We aimed to evaluate the efficacy of nasal synchronized intermittent mandatory ventilation (nSIMV) in preterm infants with primary apnea of prematurity (AOP). Forty-four preterm infants with AOP were divided into the nSIMV group or nasal continuous positive airway pressure (nCPAP) group. Clinical symptoms, signs and blood gas results following nSIMV or nCPAP were compared between the two groups. Infants receiving nSIMV had a greater reduction in apneic spells and a greater decrease in bradycardia than those receiving nCPAP. Compared with the nCPAP group, the nSIMV group had a lower incidence of respiratory support failure (9.1% vs. 27.3%; p<0.05), a lower incidence of hypercarbia (4.5% vs. 18.2%; p<0.05) and a lower incidence of gastrointestinal complications (4.5% vs. 13.6%; p<0.05). This study showed that nSIMV was more effective in respiratory support in preterm infants with AOP.