【Abstract】 Objective To investigate the clinical value of monitoring perioperative period of mechanical ventilation extubation in preterm infants with less than 34 weeks using continuous dynamic lung ultrasound. Methods In January 2014July 2017, 125 preterm infants who need mechanical ventilation for <34 gestational weeks are enrolled in this study. They were divided into ultrasound guidance group (57 cases) and non ultrasound guidance group (68 cases). The mechanical ventilation tube drawing success rate, safety, and the incidence of adverse reactions after extubation were observed.Results Compared with non ultrasound guidance group, ultrasound guidance group had high success to remove mechanical ventilation (930% vs. 765%，P=0014). Moreover, ultrasound guidance group had more markedly efficacy and less invalid than that of non ultrasound guidance group during mechanical ventilation extubation. The incidence of tachycardia, irritability and feeding intolerance in non ultrasound guidance group were higher than that i ultrasound guidance group. There had no difference on electrolyte disorder and hyperglycemia between the two groups (all P＞005). Conclusion This study demonstrates that continuous dynamic lung ultrasound for monitoring perioperative period of mechanical ventilation extubation in preterm infants with less than 34 weeks can be well assessed the process of lung disease, help adjusting the volume of mechanical ventilation and selection of extubation time, supervises different dose of caffeine citrate applied to extubation, and improve the success ratio on removing mechanical ventilation and declined the incidence of adverse reactions.