Abstract: With hot-rolled steel Q235 in China, six specimens of buckling-restrained braces are designed, manufactured and tested. The loops’ characterization of the restoring force versus the deformation is studied. The feasibility of modeling the BRB specimen with the Bouc-Wen model is discussed, and some shortages leading to considerable errors to the restoring force, such as the absence of asymmetrically mechanical properties and plastic hardening etc, are indicated. On the basis, an improved model with three suggested parameters is established. The practical calculation formulas for the three parameters are suggested. Comparisons are made between the calculated results with the model and the tested results of both UCB (under the low cycle increasingly imposed displacement tests and earthquake induced displacement-imposed test respectively) and that of the paper. It is approved that the model performs better than the unimproved model on the hysterical loops, equivalent stiffness and damping ratio. Some suggestions are made on the structural design and analysis of BRB product tests.