a method for preparing a metal substrate for inkjet ctp , comprising : treating a metal substrate by anodizing or non - anodizing , and then applying a hydrophilic polymer paint on the surface of the metal substrate . due to the existence of nano - size or micron - size oxide particles in the hydrophilic polymer paint , the metal substrate has high specific surface energy , while the metal substrate has a certain roughness , therefore the metal substrate has ink absorbency and good abrasive resistance . the metal substrate can reduce the spread of ink droplets and produces print image having better resolution and definition . the non - anodizing method can avoid environmental pollution which is caused by waste acid and waste alkali discharge of anodizing method .