Background: This study aimed to compare the weaning rate in three mechanical ventilation methods, automatic tube compensation and pressure support ventilation with airway pressure of five and eight centimeters of water.Methods: In a clinical trial study, 105 patients admitted to the intensive care unit who needed ventilation distributed randomly in three groups of 35 individuals, under ventilation with automatic compensation tube mode (group 1), and under ventilation with pressure support ventilation with airway pressure of five (group 2) or eight (group 3) centimeters of water. The patients were placed in isolation and the rate and the time of success weaning from the device were compared between the three groups.Findings: The rate of success in weaning from the ventilator in was 88.6, 57.1 and 85.7 percent in groups 1, 2, and 3, respectively; and the difference between the groups was statistically significant (P = 0.002). Mean (± SD) time of weaning in the three groups was 6.9 ± 3.7, 8.9 ± 6.4 and 7.1 ± 10.6 days, respectively; and there was not any significant difference between the three groups (P = 0.490).Conclusion: The rate of success in weaning from the device in patients undergoing mechanical ventilation under automatic tube compensation mode was higher and therefore, selecting this mode in these patients is better. In addition, morbidity and mortality rates and hospital costs would decrease in this method and bed capacity in intensive care units which is now a major problem for hospitals and health centers would increase.