The bearing capacity and seismic performance of historical timber columns can be significantly improved by the composite strengthening with near-surface mounted steel bars and wrapped carbon fiber reinforced polymer （CFRP） strips. To investigate the restoring force characteristics of composite strengthened timber columns， the cyclic loading tests on eight square timber columns were carried out considering the influence of the number of steel bars， the wrapping form of CFRP strips， and different strengthening modes. Based on the test results， the trilinear skeleton curve of composite strengthened square timber columns was proposed. And the calculation formulas of characteristic parameters such as stiffness of elastic section， hardening section and descending section， yield load， peak load， and corresponding displacement were provided. Compared with the experimental results， the correctness of the parameter calculation method was verified. According to the characteristics of specimen hysteretic curves， the hysteretic rules of composite strengthened square timber columns were determined， and the restoring force model was established. The calculated results of the model are in good agreement with the experimental results， which can better describe the hysteretic performance of the composite strengthened square timber columns.