The a-C:H films were deposited on glasses with different substrate thickness (rising from 2mm to 26mm) by Plasma Enhanced Chemical Vapor Deposition (PECVD). The effect of substrate thickness to the deposition rate, structural variations of films was investigated by surface morphology device and Raman spectroscopy. The results show that the deposition rate, H contents of films increase, meanwhile, I(D)/I(G), G peak position decrease and all of them show strong linear relation with the increasing substrate thickness. The a-C:H film with the highest thickness presents the highest deposition rate (37.7nm/s), nanohardness (20.2GPa), elastic modulus (118.8GPa) and lowest friction coefficient (0.266).