We have investigated the dynamics of poly(sodium styrenesulfonate) (PSSNa) in aqueous solutions with and without added salt (NaCl) by use of analytical ultracentrifuge (AUC) via sedimentation velocity (SV) as a function of NaCl concentration (C-s) or PSSNa concentration (C-p). As Cs increases, the sedimentation coefficient monotonically increases, whereas the diffusion coefficient shows a minimum. On the other hand, as C-p increases, the sedimentation coefficient decreases while the diffusion coefficient exhibits a minimum at C-s < 1.0 x 10(-3) M. However, they linearly vary with C-p at C-s > 1.0 x 10(-3) M. The scaling relation between the molar mass and sedimentation coefficient or diffusion coefficient at infinite dilution indicates that PSSNa chain changes from an extended conformation to a random coil as NaCl concentration increases. Our experiments demonstrate that the dynamics of polyelectrolyte chains is mediated by interchain electrostatic repulsion, hydrodynamic interactions, and intrinsic excluded volume effect.