The composite strengthening method with near surface mounted steel bars and wrapped fiber reinforced polymer strips can improve the bearing capacity and deformation behavior of timber columns effectively, and enhance their working performance greatly. To propose the load-bearing capacity formula of short timber columns strengthened with near surface mounted steel bars and wrapped carbon fiber reinforced polymer (CFRP) strips, a total of 42 reinforced specimens (12 groups) were tested under axial compression. The test results indicated that the failure of timber columns mainly occurred where the initial defects concentrated , and the bearing capacity and deformation performance of timber columns could be improved through the composite strengthening, showing significant strengthening effectiveness.Based on the typical strength model of concrete columns wrapped with fiber reinforced polymer strips, three strength models of timber columns with wrapped CFRP strips by analyzing and fitting the relevant experiment data were proposed. Through the comparison between theoretical and test values, the feasible strength model for the calculation of timber columns confined by CFRP strips was selected, and then the calculation formula of bearing capacity for the circular timber columns with composite reinforcement method was obtained. According to the additional experiment results and the comparison calculation for test data in existed research, it can be obtained that the theoretical calculation was able to predict the test results,which verified the reliability of the formula for the calculation of the strengthened timber columns' load-bearing capacity.