Abstract: Combined with an inverted siphon pipe in the Water Diversion Project in Central Yunnan, the research on high strength steel Q460C to be used in the industries of water resources and hydropower is carried out through a 1∶1 large scale model test. The stress state and ultimate bearing capacity of the large diameter water pipe, as well as the changing law of stress and displacement during the water pressure varying from zero to the end of the blasting are obtained. Model test results show that before the hydrostatic test pressure 2.82 MPa, steel pipe stress/strain～pressure and displacement pressure curve show a good linear relationship, and the maximum stress is less than Q460C steel allow stress under the working condition of hydraulic pressure test, and the penstock works in an elastic state and can meet the requirements of strength design. The maximum blasting pressure of the model is 7.5 MPa, which is 3.3 times of the design pressure of 2.26 MPa, and a large plastic deformation is produced. It shows that the penstock made of Q460C steel has good toughness and enough safety margin, and can be applied to the inverted siphon steel pipe structure of the water diversion project in central Yunnan or similar projects.