Abstract: Polyaniline(PAN) was in-situ formed around calcium carbonate(CaCO₃) microparticles previously stabilized with polyelectrolyte layers (PEs), generating PAN/(PEs)₆/CaCO₃ hybrid microparticles. The effects of PEs and concentration of aniline monomer on the stability and morphology of the hybrid microparticles were studied. The obtained hybrid microparticles were characterized by SEM, FT-IR, UV-Vis, etc. Furthermore, the hybrid microparticles were deposited on glassy carbon electrode, which displayed high electrocatalytical activity toward the oxidation of dopamine(DA). The oxidized peak potential was negatively shifted with a value of 130 mV, compared with that using pure CaCO₃ microparticles. The modified electrode showed good reproducibility, and the relative standard deviation(RSD) was estimated to be about 4.2% in 4.0 mmol/L DA aqueous solution (n=5). The obtained hybrid microparticles have great potential in construction of biosensors. The linear range was in the range of 0.5~10.0 mmol/L, with the detection limit of 0.2 mmol/L(3S/N).