An immunoglobulin binding protein provided by the invention comprises variants of the B structural domain of a protein A, the C2 structural domain of a protein G and the B3 structural domain of a protein L or a combination of any one to three of the variants. The protein A, the protein G and the protein L have different binding characteristics and certain complementarity, so the immunoglobulin binding protein is an alkali-resistant multifunctional IBP molecule with wide reactivity and high affinity. The protein is purified by a three-step chromatography method, so that the protein quality canbe stabilized, the protein purity is more than 97%, the endotoxin level is lower than 1 Eu/mg, and the requirement of clinical protein is met. The stability of an immunoadsorption filler synthesized from the purified immunoglobulin binding protein is improved, so the use frequency of the filler can be effectively increased, and the service life of the filler is prolonged.