Objective: To analyze the difference of residual and absorbed postoperative intracranial gas in the surgical treatment of chronic subdural haematoma between the "single-hole, single-tube drainage" and the modified "single-hole, double-tube flushing and venting" + postoperative "single-hole, single-tube drainage" surgical approach. The differences in the residual and absorption of postoperative intracranial gas in the surgical treatment of chronic subdural hematoma. Methods: Patients with chronic subdural haematoma who underwent surgery from September 1 in 2016 to October 31 in 2022 in our hospital(South Zone) were selected for the retrospective study, and divided into experimental group(55 cases) and matched group(66 cases) according to the different surgical methods. All patients were treated with the same care and treatment protocols after surgery. The age at the time of hospitalization, duration of surgery, GCS score at admission, duration of hospital stay, amount of postoperative intracranial pneumonia, amount of intracranial pneumonia at extubation, infection rate and recurrence rate of the patients in both groups were statistically analyzed. Results: The number of patients attending our hospital with chronic subdural haematoma has tended to decrease in the last two years. There was no statistically significant difference between the two groups in terms of age, time of surgery, Glasgow coma scale(GCS) score at admission, days in hospital, clinical symptom improvement and treatment efficiency, and infection rate(P>0.05). 121 cases had a postoperative review of cranial CT in both surgical procedures indicating haematoma clearance rate more than 90%, all patients had postoperative symptom relief(including disappearance, significant relief and remission), and at discharge, the GCS score could reach 15 in all cases, and the overall efficiency rate could reach 100% in both groups. In comparison of postoperative intracranial gas volume, intracranial gas volume at extubation and postoperative recurrence rate, there were 4 cases of infection(6.1%) in the matched group and 1 case of infection(1.8%) in the experimental group(P=0.244), 5 recurrences(7.6%) in the matched group and no recurrences in the experimental group(P=0.045). Conclusion: In the drilling surgical treatment of chronic subdural hematoma, both surgical options are safe and effective, in which the modified single-hole single-tube flushing, venting and drainage can reduce the postoperative intracranial gas volume and intracranial gas volume more during extubation, thus reducing the postoperative recurrence rate.