Molecular dynamics simulations were performed based on the all-atom (AA) force fields for three kinds of acyclic guanidinium-based ionic liquids (ILs), which composed by dimethyldihexylguanidinium cation and three different types of anions. The force field parameters were developed based on our previous work for guanidinium-based ILs [X. Liu, S. Zhang, G. Zhou, G. Wu, X. Yuan, X Yao, J. Phys. Chem. B 110 (2006) 12062-12071; X. Liu, G. Zhou, S. Zhang, G. Wu, G. Yu, J. Phys. Chem. B 111 (2007) 5658-5668]. Validation was carried out by comparing simulation densities with experimental data, and they are in good agreement. Dynamics properties including the coefficient of self-diffusions, viscosities and molar conductivities for these lLs were predicted. To depict the microscopic structures of the ILs, both spatial distribution functions and radial distribution functions were investigated. (c) 2008 Elsevier B.V. All rights reserved.