Abstract: A protein substrate includes a base having micro-passages and reaction grooves, a polyethyleneimine (PEI) fixed on the base and a specific protein fixed on the PEI. The base is modified by plasma stripper to make the PEI bonded on the base. Mixed with tyrosinase, the specific protein can stably stick on the base due to the tyrosinase bonded with the PEI. By antigen-antibody bonding specificity, the invention can quickly detect antibody in a sample able to link with the specific protein. The specific antibody can be added with targeted biotin secondary antibody, targeted avidin-peroxidase, and color producing substrate able to react with the targeted avidin-peroxidase, such as tetramethylbenzidine or 3-(4-hydroxy)phenyl propionic acid (HPPA), so as to measure a specific antibody amount.