Objective To compare the humidification effect of the MR410 humidification system and MR850 humidification system in the process of mechanical ventilation. Methods Sixty-nine patients underwent mechanical ventilation were recruited and randomly assigned to a MR850 group and a MR410 group. The temperature and relative humidity at sites where tracheal intubation or incision, the absolute humidity, the sticky degree of sputum in initial three days after admission were measured. Meanwhile the number of ventilator alarms related to sputum clogging and pipeline water, incidence of ventilator associated pneumonia, duration of mechanical ventilation, and mortality were recorded. Results In the MR850 group,the temperature of inhaled gas was ( 36. 97 ±1. 57) ℃, relative humidity was ( 98. 35 ±1. 32) % , absolute humidity was ( 43. 66 ±1. 15) mg H2O/L, which were more closer to the optimal inhaled gas for human body.The MR850 humidification system was superior to the MR410 humidification system with thinner airway secretions, less pipeline water, fewer ventilator alarms, and shorter duration of mechanical ventilation. There was no significant difference in mortality between two groups. Conclusions Compared with MR410 humidification system, MR850 humidification system is more able to provide better artificial airway humidification and better clinical effect.