Objective To compare the different characteristics of adaptive support ventilation(ASV) and synchronized intermittent mandatory ventilation-pressure support ventilation(SIMV-PSV) mode in weaning patients after coronary artery bypass grafting and seek a more suitable weaning mode. Methods Prospective study enrolling 50 patients who received coronary artery bypass grafting from January 2007 to June 2010 was performed. After cardiac surgery, the patients were transferred to ICU and divided into ASV group and SIMV-PSV group randomly. Respiratory weaning progressed through 3 phases following the standard procedure and the patients were extubated if 3 phases all accorded with weaning condition. Duration of intubation, duration of mechanical ventilation, success rate of fast-track extubation, condition of breathing mechanics and hemodynamics, ventilator alarms, and ventilator settings manipulations before extubation were compared between the two groups. Results Forty-five patients including 22 patients in ASV group and 23 patients in SIMV-PSV group completed the study. Compared with SIMV-PSV group, parameters in ASV group, such as duration of mechanical ventilation[(213.9±65.4) vs (309.2±71.2)min], duration of intubation[(244.5±72.9) vs (338.3±85.6)min], success rate of fast-track extubation(90.9% vs 60.9%), ventilator alarms[(2.2±1.8) vs (4.2±2.1)times/min], ventilator settings manipulations[(4.6±2.0) vs (9.3±4.3)times/min] were significantly different(P＜0.05). As for condition of breathing mechanics, mean airway pressure in ASV group was significantly lower than that in SIMV-PSV group[(7.5±1.1) vs (11.6±1.4)cmH2O, P＜0.05] and pulmonary dynamic compliance in ASV group was better than that in SIMV-PSV group[(65.3±12.3) vs (50.4±11.8)ml/cmH2O, P＜0.05]. There was no significant difference in hemodynamics and blood gas analysis between the two groups (P＞0.05). Conclusion ASV weaning mode is safe and effective, which could accelerate the extubation and simplify the manipulation.