The cloud-point temperatures (T-clo's) of poly(N-isopropyl acrylamide) (PNI-PAM)/water solutions with NaCl, NaBr, or NaI were measured. All these salts reduced the T-clo's of PNIPAM/water solutions to different extents, in the following order: NaCl > NaBr > NaI. The higher the concentration of the added salt was, the more greatly T-clo dropped. A dynamic viscoelasticity investigation of the PNIPAM/water solutions with the salts indicated that during phase separation, the system changed from a homogeneous fluid into a physically crosslinked network, and the addition of salts also reduced the temperature at which this change began. The gelation temperature (T-gel,) and the scaling exponent of the PNIPAM/water solutions with NaBr were obtained with dynamic scaling theory, and T-gel was found to be close to T-clo. That the addition of salts to the solution decreased T-clo and T-gel to the same extent further proved that the network structure was formed with the phase separation in the PNIPAM/water solutions.