The filming process of polystyrene nanolatex (NPS) particles was studied by a combination of various methods. For a constant annealing time of 1 h, the AFM images showed that the deformation and interdiffusion temperatures of NPS particles were ca. 90 and 100-110degreesC, respectively. In spin-lattice relaxation measurements of solid state NMR, it is found that T-1L, T-1S, and P-L increased significantly after annealing at 90 and 100degreesC for 1 h. DSC results showed that there was a exothermic peak near T, after annealing for 1 h at the elected temperatures below 95degreesC; otherwise, the exothermic peak disappeared after annealing at 100degreesC or above. The apparent density of NPS increased suddenly in the temperature range of 90-110degreesC. The results indicated that the macromolecules are highly constrained in NPS particles, leading to higher conformational energy, with more free volume and segments less restricted, which are the driving forces for the particles sintering at a lower temperature compared to the micro-PS particles with larger diameter.