The formation of polyaniline (PANI) in the reverse micelles of poly(oxyethylene) nonylphenyl ether, $(NP5, H(CH_2)_9Ph(OC_2H_4)_5OH)$, was investigated by small-angle neutron scattering (SANS). The reverse micellar solution containing initiators in the inner part of reverse micelle was prepared with surfactant (NP5), water, cyclohexane and an initiator (ammonium persulfate (APS)). The core-shell sphere model containing smearing effect reveals that the polymerization occurs on the shell layer of the reverse micelles. Shell thickness averages varied from 48 $AA$ to 109 $AA$ with increases of monomer concentration.