The acute respiratory distress syndrome (ARDS) was first described in the medical literature in 1967. Patients with ARDS mostly require mechanical ventilatory support due to hypoxic respiratory failure. Mechanical ventilation can induce lung injury (ventilator-induced lung injury, VILI) by causing overdistention and repetitive opening and closing of unstable lung units. Data from a number of randomized controlled trials indicate that a lung protective ventilatory strategy with small tidal volume and low plateau pressure reduces mortality in acute lung injury (ALI) and acute respiratory distress syndrome. Lung recruitment maneuvers are being used in the management of ALI and ARDS, but recruitment maneuvers are still controversial. Lung recruitment maneuver is aimed to open the collapsed lung and keep the lung open. The maneuver briefly increases the alveolar pressure to open recruitable lung, sustained with adequate positive end-expiratory pressure(PEEP) after lung recruitment, to avoid derecruitment. We want to enroll 120 patients with early ALI/ARDS in this randomized controlled study. The study group use recruitment maneuver and lung protective ventilatory strategy, and the control group use lung protective ventilatory strategy only. Concerning about both safety and efficacy, we design a modified recruitment maneuver protocol which has never been published in previous medical literature. The primary outcome is ventilator-free days and ICU-free days, and secondary outcomes include ventilator weaning rate, and 28-day mortality and cost effectiveness analysis. Since no randomized controlled trials clearly establish benefit from recruitment maneuvers, we hope this study would be able to provide some evidence on whether lung recruitment should be used in the routine management of ALI/ARDS.