The multilayer DLC films consisting of sp(2)-rich DLC layers (soft DLC) and sp(3)-rich DLC layers (hard DLC) with different modulation ratios (thickness ratio of the hard DLC to soft DLC) ranging from 2:1, 1:1 to 1:2 had been deposited on Si (100) wafer and Ti-6Al-4V alloy substrates by filtered cathodic vacuum arc (FCVA) deposition. The effect of modulation ratio on the microstructure and properties of the multilayer DLC films including sp(3) content, residual stress, mechanical properties, adhesion strength and wear resistance were studied by Raman spectroscopy, profilometry technique, nanoindenter, Vickers indentation test, scanning electron microscopy (SEM) and ball-on-disc reciprocating friction test. The results showed that the sp(3) content and the hardness of the multilayer DLC films decreased with modulation ratios decreasing. The stress of the multilayer DLC films could be effectively reduced and the stress decreased with the modulation ratio decreasing. The multilayer DLC film with modulation ratio of 1:1 had the best wear resistance due to a balance between hardness and residual stress. (C) 2012 Published by Elsevier B.V.