Abstract: Objective: To evaluate the surgical operation for treatment of Chiari malformation associated with hydromyelia. Methods: Thirteen patients with Chiari malformation associated with hydromyelia, which were diagnosed with magnetic resonance imaging(MRI),and treated by surgical operation were retrospectively studied. Results: The mean follow-up periods were 2.1 years. The degree of reduction of the volume of syrinx cavity on sagittal MRI was significant after operation. Conclusions: Cisterna magna reconstruction is a safe and effective way for the treatment of Chiari malformation associated with hydromyelia.