Objective:To investigate the protective effect of external diaphragm pacing（EDP）combined with hyperbaric oxygen（HBO）therapy on preventing ventilator-induced diaphragm dysfunction（VIDD）and its related mechanism.Methods:A total of 100 adult male rats were randomly divided into five groups：blank control（BC）group，VIDD group，EDP group，HBO therapy group，and the combination of EDP and HBO therapy（EDP+HBO）group，with 20 rats per group. After tracheotomy，the BC group received no treatment，while the rats in the other four groups were given controlled mechanical ventilation to establish the VIDD rat model. And after successful modeling，the VIDD group did not receive further intervention，and the other three groups were treated accordingly. After 10 days of consecutive treatment，the changes in diaphragm weight（DW）and DW/body weight（BW），contraction force of diaphragm in vitro，and transection area of muscle fibers of each group were measured. Gene and protein expressions of diaphragm-related factors were detected. Results:Compared with the BC group，the DW，DW/BW，the transection area of muscle fibers，and the fiber structure and the contraction force of diaphragm in vitro of the VIDD group were decreased significantly. The expression levels of MHC-1，Keap1，Drp1，atrogin-1，MuRF-l，caspase-3，and beclin1 in the VIDD group were significantly increased while the expression levels of MHC-2，p-Akt，Mfn2，Nrf2，SOD，and GSH-Px were significantly decreased after treatment（ P < 0.05）. Compared with the VIDD group，the EDP+HBO group had higher DW and DW/BW［（0.35 ± 0.02）g vs.（0.63 ± 0.06）g，0.78 ± 0.08 vs. 1.34 ± 0.06，both P<0.05］，stronger contraction force of diaphragm in vitro［（1.15 ± 0.42）N/cm 2vs.（2.19 ± 0.10）N/cm 2， P < 0.05］，declining expression levels of MHC-1，Keap1，Drp1，atrogin-1，MuRF-l，caspase-3，and beclin1，increased expression levels of MHC-2，p-Akt，Mfn2，Nrf2，SOD，and GSH-Px，and much better diaphragmatic function，and all the differences were statistically significant（ P<0.05）. Conclusion:External diaphragm pacing combined with HBO therapy can significantly mitigate and decelerate VIDD by increasing the contraction force of the diaphragm，and reducing the oxidative stress，diaphragmatic atrophy and structural injury.