CSR, a new accelerator project at the Heavy Ion Research Facility in Lanzhou (HIRFL), is a multipurpose Cooling Storage Ring (CSR) system that consists of a main ring (CSRm) and an experimental ring (CSRe). In order to satisfy the requirements of the beam injection and extraction, four magnetic septa will be used in the injection and extraction systems for the two storage rings. The choice of the type, the electric-magnetic design and the field calculation will be introduced in this paper, including the construction and mechanical design, the fabrication and the test.