With the development of die industry, the number and variety of die springs with special-shaped cross-section are increasing day by day because of their characteristics such as high stiffness, small volume and long service life. At present, except for the strong spring with square section, the design methods of strong springs with other sections are mostly based on specific sections. Through experiments, the so-called empirical design formula derived from the correction coefficient has the following characteristics: 1. Excessive use stress is the main reason for spring failure. Under the same conditions, the life of wire spring with special section is longer than that of wire spring with circular section 13- 14%. 2. In the same space, the bearing capacity of the steel wire spring with square section is 43-48% higher than that of the spring with circular section and 50% higher than that of the spring with rectangular section. 3. The steel wire spring with special section can produce large deformation and heavy weight. 4. The linearity is better than that of the circular section spring, that is, the stiffness tends to be constant, especially for the spring whose long side is parallel to the axis. The circular cross-section material cannot reach the design load; Where the spring installation space is small; In the case of replacing the circular cross-section composite spring, strict spring characteristics are needed.