Inclusion Criteria:  Patients undergoing general anesthesia in our hospital; Ages 18-60; American Society of Anesthesiologists (ASA) grade ⅱ ~ III , no severe respiratory, circulation, liver, kidney, coagulation function abnormalities; Expected duration of operation >2h; Surgical grade 2-4; No serious lung infection and lung disease; Body mass index (BMI) 18~30 kg/m2; There are no contraindications for electroacupuncture stimulation.  Exclusion Criteria:  Patients with severe circulatory or other system dysfunction; Patients with pulmonary and one-lung ventilation; Unwilling to cooperate with the patient; Patients with low compliance.