Highly polar polyacrylonitrile (PAN) is being widely used in the production of high-performance fibers and electronic industries. The polar solution dope, however, raised complicated rheological problems resulting from the phase change with environmental conditions such as ageing temperature and time. Hence, it has a real significance to estimate the physical properties of the spinning dopes of the polar polymer solutions with temperature and time at the static and sheared states. We prepared two typical PAN solution dopes in N,N-dimethyl formamide (DMF) and dimethylsulfoxide (DMSO) and discuss how to evaluate the characteristic features of the polar solution dopes on rheological basis in relation with dynamic light scattering and phase morphology. With increasing temperature, the intrinsic viscosity and hydrodynamic diameter of dilute solutions were decreased but the dynamic viscosity of concentrated solutions was increased. PAN solutions became more heterogeneous with increasing temperature and time. Of two solutions the effects were more prominent with DMF than with DMSO. This indicated that high polarity of nitrile groups causes enthalpy-driven polymer aggregation at higher temperature and prolonged time. Keywords: Polyacrylonitrile solution, DMF, DMSO, rheological properties