Abstract: Theoretical analysis and distorted model tests are performed to study the hydraulic characteristics of long-distance pressure diversion tunnel. The water diversion project from the Second Songhua River to central cities in Jilin Province is taken as an object. By comparing test data with theoretical analysis, the validity  of the distorted model is verified. The characteristics of hydraulic oscillation in long-distance pressure tunnel are found as long wave cycle of surge chamber and slow attenuation, etc.