Abstract:The study of stress distribution of infinite long plate with the counterpoint load is helpful to further understand and solve the problem of lateral calculation simplification of long strip plate structures (such as bridge structures with overhanging beam). Its equivalent loading mode (plane stress problem) also corresponds to the force problem (plane strain problem) of soft soil subgrade with the subjacent under the strip foundation. Through the theoretical analysis, the method of complex variable function is used to obtain the stress calculation formula of the infinite long plate strip with counterpoint load, and then the effective-width simplified calculating method of the theoretical solution is derived. The error control of the theoretical solution is within 5%, which makes the theoretical preparation for further engineering application.