The rotation degree of freedom in discontinuous deformation analysis (DDA) may cause false volume expansion when a block undergoes a large rotation. We propose a block displacement function to prevent this defect. Specifically, the degrees of freedom in a block are redefined by incremental displacements at its vertices, and displacement is formulated based on the mean value coordinates. In addition, the finite element method with updated Lagrangian formulation is employed to derive the equilibrium equations, while the contact analysis and implicit time integration for dynamics is maintained from the original DDA. After each time step, the block configuration is updated by adding the new degrees of freedom to the previous coordinates of the block vertices. Results from numerical examples confirm the effectiveness of the proposed approach to prevent false volume expansion, ensure correctness of contact analysis, and provide realistic stress results when simulating large rotations. K E Y W O R D S discontinuous deformation analysis (DDA), false volume expansion, mean value coordinates 1 INTRODUCTION Discontinuous deformation analysis (DDA), originally proposed by Shi, 1 allows to effectively analyze the mechanical behavior of a discrete block system subject to large displacements. 2 In addition, DDA can handle discontinuity and has been adopted to address diverse geotechnical problems, such as landslide simulations, 3,4 rock slope stability evaluation, 5,6 rockfall trajectory tracking, 7 blasting effect evaluation, 8 shear creep deformation analysis of structural planes, 9 crack propagation modeling, 10,11 and seismic wave propagation modeling. 12 Various enhancements have been 4768