A novel and facile approach to fabricate photoactive polyaniline/titania/silicon coatings with 3D compound-eye structures was reported, based on anisotropic wet etching, hydro-thermal synthesis and chemical oxidation. For 3D compound-eye coatings, the choice of materials and design of structures were well-founded. The composite coatings exhibited broadband antireflection property (less than 3.2% of reflectivity at wavelengths from 200 to 2400 nm), super-hydrophilicity with a static contact angle of 0.7° and double p/n hetero-junctions, exhibiting superior photocurrent. It further demonstrated that by exploiting the advantages of this method, the application of such structures in the photocatalytic area is thus straightforward.