This study is a clinical randomized controlled study.The objective of this study is to compare the prognosis of patients with ARDS between eit-v / q-oriented individualized ventilation strategy and traditional lung protection ventilation strategy, and to establish the demonstration application of eit-v / q-oriented ventilation strategy in ARDS

Inclusion Criteria:

1. According to ARDS Berlin standard, ARDS, PaO2 / FiO2 < 200mmhg, peep > 5cmh2o;
2. According to clinical judgment, lung recruitment therapy is needed due to hypoxemia;
3. The subjects or their families signed informed consent.
4. Admission to ICU was less than 72 hours;
5. The estimated duration of mechanical ventilation was more than or equal to 48 hours;
6. Age ≥ 18 years old and ≤ 80 years old;

Exclusion Criteria:

1. The patients with heart implants could not be monitored by EIT;
2. Patients or their families refused to participate in the study;
3. Hypernatremia