Background: Nanotechnology has received considerable attention and developed rapidly due to some superior properties of nanomaterials. As one of the most important conductive materials, polyaniline with various nanostructures have shown good environmental stability, charge transport capacity, ease of synthesis, flexibility in processing and good biocompatibility. They have been used in many fields such as solar battery, electroluminescence, electromagnetic shielding, rechargeable batteries, material corrosion protection and biomedical applications.Objective: We mainly review the synthesis, dispersion techniques of polyaniline nanoparticles so that they can be well dispersed and more widely used in biomedical field. Method: We searched and collected more than one hundred references, focused on the methods for synthesis, dispersion and biomedical applications of polyaniline nanoparticles. Results: The synthesis methods of polyaniline nanoparticles mainly include micro-emulsion polymerization, interfacial polymerization, a pulsed potentiostatic method et al. The dispersion method of polyaniline nanoparticles can be classified as chemical method and physical method. Biomedical applications of polyaniline nanoparticles in biosensors, neural probes, tissue engineering and photothermal therapy for cancer are also discussed. Conclusion: This review provides the comprehensive collections of information that has clearly given ideas of methods for preparation and dispersion of polyaniline nanoparticles and their recent advanced biomedical applications.