Abstract: Objective:To investigate the clinical effects and incidence of complications of two different surgery approaches in the treatment of Chiari Ⅰ malformation.Methods:Forty-two patients with Chiari Ⅰ malformation were divided into the group A(19 cases) and group B(23 cases) according to the surgery approach.The groups A and B were treated with posterior cranial fossa bony decompression and posterior cranial fossa bony decompression,expanding the dural repair combined with cerebellar tonsillar resection,respectively.Results:The valid treatment in 11 cases and invalid treatment in 8 cases were found in group A,the effective rate of which was 57.89%,and the valid treatment in 21 cases and invalid treatment in 2 cases were found in group B,the effective rate of which was 57.89%.The treatment effect in group B was better than that in group A(P<0.05).The postoperative complications were found in 2 cases of group A(10.53%) and 10 cases of group B(43.48%),and the total incidence rate of the postoperative complication in group B was higher than that in group A(P<0.05).Conclusions:The treatment effect of Chiari Ⅰ malformation with posterior cranial fossa bony decompression,expanding the dural repair combined with cerebellar tonsillar resection is good,but incidence rate of the postoperative complication of which is high.