The effectiveness of the improve Tuned Liquid Column Damper (iTLCD), as known as one of liquid damper types, which overcomes the practical difficulties involved in the implementation of the conventional TLCD for short period structures by tuning the frequency of the damper to the structural frequency, is studied for reducing the dynamic response of the structure due to earthquake excitations in this paper. The formulations of the iTLCD connected by a spring to the short period stiff structure due to seismic excitation are established based on the TLCD. And then, the characteristic parameters of the iTLCD are chosen based on the optimal ratios in each studying case. Therefore, the effectiveness of the iTLCD is investigated in three cases of earthquake excitations with and without the damper. The results show that the iTLCD affects significantly on the dynamic response of the structure under seismic excitations, and then it is more decreasing the dynamic response than without the damper. However, the effectiveness of the iTLCD depends on the dynamic character of the structure, excitation loads, and the characteristic parameters of the iTLCD. Hence, in the practical design problem, the property parameters of the structure will be fixed, and then the characteristic parameters of the iTLCD will be chosen based on the optimal ratio to have the best performance for mitigating the dynamic response of the structure under dynamic excitations. (C) 2019 The Authors. Published by IASE.