With a focus on the intake tower of the Yanshan Reservoir, this paper discusses the method of modeling in the 3D CAD software SolidWorks and the interface processing between SolidWorks and the ANSYS code, which decreases the difficulty in modeling complicated models in ANSYS. In view of the function of the birth-death element and secondary development with APDL (ANSYS parametric design language), a simulation analysis of the temperature field and thermal stress during the construction period of the intake tower was conveniently conducted. The results show that the temperature rise is about 29.934 ℃ over 3 or 4 days. The temperature differences between any two points are less than 24 ℃. The thermal stress increases with the temperature difference and reaches its maximum of 1.68 MPa at the interface between two concrete layers.