Abstract: Objective To compare the clinical effectiveness of different ranges of bony decompression for the treatment of Chiari malformation type I.Methods A total of 162 patients with Chiari malformation type I who underwent surgical treatment in the Affiliated Hospital of Xuzhou Medical University from January 2016 to July 2022 were enrolled and their clinical data were retrospectively analyzed. According to surgical types, they were divided into two groups:a preservation group (n=99) and a resection group (n=63). Patients in both groups underwent posterior fossa decompression + tonsillectomy +duraplasty, where the posterior arch of atlas was removed in the resection group but retained in the preservation group. Both groups were compared for the duration of surgery, perioperative blood loss, the Chicago Chiari Outcome Scale (CCOS) scores and resolution of syringomyelia at postoperative six months were compared. Furthermore, the length of hospitalization stay and postoperative complications were recorede and compared.Results There was no statistical difference in perioperative blood loss, the length of hospitalization stay and CCOS scores and the recovery of syringomyelia between the two groups (P>0.05). However, the duration of surgery was significantly longer in the resection group than that in the preservation group(207.17±55.87) min vs (188.36±56.37) min (P<0.05). The incidences of postoperative fever, intracranial infection and poor incision healing were significantly higher in the resection group than those in the preservation group (P<0.05).Conclusions Both types of the surgery are effective in improving syringomyelia and long-term CCOS scores, without significant difference in effectiveness. Intraoperative preservation of the posterior arch of atlas can save operative time and reduce the incidences of complications such as postoperative fever, intracranial infection and poor incisional healing.