The invention discloses a method for detecting the content of target protein in to-be-detected samples. According to the method, through introduction of a target protein antibody and fusion protein, biotin-avidin systems are connected through interaction with antigen-antibody to achieve different series of amplification, wherein the target protein antibody can be tightly integrated with the targetprotein, and the fusion protein with different numbers of bap peptide fragments is catalyzed by BirA protein in the body of escherichia coli to be modified by biotin. Experiments prove that by the method, the content of the target protein in the to-be-detected samples can be detected, and the type, the proportion and the concentration of the fusion protein can be adjusted according to the concentration of the target protein to meet different detection demands. The method has high application value.