The work aims to prepare uniform-size nanoscale self-healing microcapsules with polypyrrole as organic capsule wall and TiO2 as the inorganic capsule core and discuss its formation mechanism. Organic/inorganic composite self-healing microcapsules were synthe-sized by chemical oxidation polymerization under an ultrasonic condition. Effects of different preparation technologies on grain size, morphology and structure were studied by means of SEM, XRD and FT-IR. The results indi cated that the anionic surfactant was more beneficial to the surface coating of polypyrrole on TiO2 particles. Under the effects of sodium dodecyl benzene sulfonate (SDBS) and ultrasonic wave, the polypyrrole monomer aggregated with TiO2 as the core and formed polypyrrole capsule wall to obtain a spherical PPy-TiO2 composite namo microcapsule of uniform grain size and diameter of about 100 nm. A modified layer is formed due to chemisorptions of the anionic surfactant on TiO2 powder surface, which can inhibit spontaneous agglomeration of TiO2 and promote coating and agglomeration of polypyrrole monomer on its surface.