With the continuous access of new "source" and "load" to the distribution network, the problem of frequent voltage fluctuations in the distribution network is becoming more and more serious. To address this problem, a multi-timescale voltage refinement in dual voltage levels based on the synergy of hybrid distribution transformer and OLTC is proposed. Among them, the MV side relies on the traditional On-Line Tap Changer transformer (OLTC), and the LV side adopts the Hybrid Distribution Transformer (HDT), which is constructed based on the consideration of the different response characteristics of the two kinds of distribution equipment, and the integrated control strategy of voltage at different time scales under dual voltage levels is proposed. The dual voltage integrated control model is constructed based on the consideration of the different response characteristics of the two kinds of distribution equipment. Finally, under the MATLAB/Simulink environment, the simulation examples of medium- and low-voltage distribution networks are constructed, and the simulation results show that the voltage control strategy can effectively solve the voltage overrun problem of medium- and low-voltage users, and at the same time, it can reduce the total voltage deviation of the distribution network.