The power draw for material movement is an important design parameter for the motor/drive train of industrial rotary drum systems. It is also the valuable process information reflecting working conditions of the drum. Most power draw calculation methods assume that the particles are mono-sized or evenly distributed, and the drum has no axis offset. However, these assumptions may not be always satisfied. In the present work, the power draw for material movement in a rotary drum filled with multi-dispersed particles is investigated using an experimentally validated DEM model. The effects of axis offset, rotational speed and filling degree of the drum are studied. Discrete Fourier Transform is performed to capture features of the simulated power draw profile. It is found that periodicity of the power draw profile is caused by axis offset of the drum, and its frequency is equal to the rotational frequency of the drum. Regression analysis shows that the peak and mean of the power draw is proportional to rotational speed and filling degree. The axis offset of the drum has no significant influence on the mean power draw, but it determines greatly the overshoot. Result of the work contributes to a better understanding of the power draw from microscopic and macroscopic view. It has potential usage for online monitoring of the axis offset of industrial rotary drums to prevent motor damage. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.