Abstract: Objective To investigate the damage rate of the air flow sensor caused by the flow velocity and pressure in the process of mechanical ventilation and spray. Methods 12 wire type flow sensor were randomly divided into flow rate trigger group and pressure trigger group. Every time sprayed 15 minutes,then removed flow sensor, a total number of times gathered statistics when flow sensor failed, statistical analysis was performed using SPSS software. Results The flow rate trigger group was 410.83±29.8 times and was significantly less than that of the pressure trigger group of 955.67±84.54 times, the difference was statistically significant (P<0.05). Conclusions The flow rate trigger during the process of mechanical ventilation and spray was significantly increased the damage rate of output flow sensor comparing with pressure trigger.