Photoinitiated inverse emulsion polymerization of sodium acrylate (AANa) in kerosene was carried out at room or lower temperature, using 2,2-dimethoxy-2-phenylacetophenone (DMPA) as the initiator. Kinetic investigations indicated that the polymerization could be completed in about 30 min and produce polymer with high molecular weight (106~107). It was found that monomer droplets are the main sites for the polymerization (nucleation). With the increase of DMPA concentration, polymerization rate (Rp) reaches a maximum value while molecular weight of the produced polymer has an adverse result, but the dependence of Rp on incident light intensity is similar. Influences of other parameters such as monomer concentration, emulsifier content and reaction temperature, etc. were also studied. At lower pH values of water phase, Rp depends strongly on the pH due to the electrostatic interaction between the ionized radicals and the monomers. At higher pH, Rp shows a slight dependence on pH.