The invention relates to a target protein-induced deoxyribonuclease (DNase) cycle generation-based homogeneous immunoassay method. A detection solution of the immunoassay method is prepared from an antibody 1-DNA1 conjugate, an antibody 2-DNA2 conjugate, hemin, exonuclease III and DNA3 / DNA 4 double-stranded DNA. When a target protein exists, the target protein can be immunologically recognized by the antibody 1-DNA1 conjugate and the antibody 2-DNA2 conjugate at the same time; based on an ortho effect, a complex is formed by hybridizing DNA1 and DNA2 and then has a chain substitution reaction with DNA3 on the double-stranded DNA, so that DNA4 rich in a G4 sequence is released and combines with the hemin so as to form G-quadruple chain / hemin DNase; in addition, the DNA3 reacting with the DNA1 and the DNA2 can be recognized and cut by the exonuclease III, so that the DNA1 and the DNA2 can undergo a chain substitution reaction with another DNA3, and another DNA4 is accordingly released to produce DNase; therefore, if repeating in this way, a large amount of DNase can be produced. The DNase can catalyze the color development of tetramethylbenzidine (TMB) and the luminescence of luminol, and can be used for carrying out sensitive quantitative analysis on the target protein by means of color comparisons and chemiluminiscence. The immunoassay method is simple to operate, rapid, sensitive and high in universality, and has a certain clinical application value.