An immunoglobulin binding protein provided by the present invention includes the B domain of protein A, the C2 domain of protein G, the variant of the B3 domain of protein L or any combination of 1-3 variants thereof, through protein A The different binding properties of protein G and protein L have certain complementarity, and they are alkali-resistant multifunctional IBP molecules with wider reactivity and higher affinity. In the present invention, the three-step chromatography is used to purify the protein, which can stabilize the protein quality, ensure the protein purity is greater than 97%, and the endotoxin level is lower than 1Eu / mg, meeting the requirements of clinical protein. The stability of the immunoadsorption filler synthesized by the purified immunoglobulin binding protein is increased, which can effectively increase the use times of the filler and prolong the service life of the filler.