this paper, a novel semi-active magnetorheological tuned liquid column damper (MR-TLCD) device combining tuned liquid column damper (TLCD) and magnetorheological damper (MRD) is devised for wind or earthquake vibration control of civil structures. In this device, a traditional moving head loss in the TLCD is replaced with a controlled MRD in the bottom or one side of the vertical column, which can easily and rapidly adjust the damping of the device. A semi-active experimental prototype MR-TLCD consisting of a shear rotary MRD and a TLCD is built. Based on the four basic presumptions, a dynamic model of the devised MR-TLCD is established using the Lagrange equation. In this equation, the formula of MRD employs the Bingham Boltzmann model. The natural frequency of the MR-TLCD is determined by the total central length and spring stiffness. It is worth noting that the natural frequency differs with the simple TLCD, because the device adds a joint spring. An equivalent linear damping expression is developed under harmonic excitation, and its mechanical model is developed using the equivalent period displacement and the coulomb friction force of MRD. At the same time, the equivalent damping can be adjusted by the real-time applied current, which can achieve the semi-active control performance. To validate the proposed frequency and damping model, Experimental test is conducted on a section area 150mm × 150mm and a total length 2.24m of the MR-TLCD dimensions. Comparisons are made between predicted and measured TLCD liquid surface displacement motion. The result shows the error of its nature frequency is only 2.29%.