pH-sensitive spherical micelles with obvious core-corona structure were fabricated by self-assembling of block copolymer of methylacrylic acid and macro-monomer FM [CH2=C(CH3)OOCH2CH2(OCOCH2CH2CH2CH2CH2)(5)OH] (PMAA-b-PFM). Transmission electron microscopy and laser light scattering studies showed that micelles were nanoscale with narrow size distribution. Solution pH value and the micelle concentration strongly influenced the hydrodynamic radius of the spherical micelles (32-90 nm). The obtained polymeric micelles should be useful for biomedical materials such as drug delivery vehicles.