In this study, we prepared exfoliated nanocomposites from polyvinyl acetate (PVAc) and organic montmorillonite (OMMT) through different synthesis processes. OMMT was exfoliated into layers or sheets of nanoparticles. They dispersed in PVAc matrix randomly. The synthesis processes influenced the dispersion and apparent viscosity significantly. PVAc and PVAc-OMMT both were pseudo-plastic Non-Newtonian fluids and had the normal stress effect (or Weissenberg effect) from pole-climbing phenomenon. By analyzing the apparent viscosity using power-law function equation, Newtonian fluid flow equation, and Cross-Williamson model viscous equation, the synthesis processes and OMMT had a combined effect on the rheology of PVAc and PVAc-OMMT. With the change of synthesis processes and the increase of OMMT content in synthesis system, the calculated molecular weight of PVAc-OMMT increased.