The present invention relates to the technical field of protein biological functions, in particular to a polypeptide, a fusion type multimeric protein and use thereof, the polypeptide is selected from: (1), a polypeptide having a substitution mutation in at least one position selected from the group consisting of positions 16, 25, 29, 49 and 58, as compared with a natural C structural domain of a protein A as shown in SEQ ID NO.1; wherein, the position 16 is subjected to a substitution mutation into leucine or valine; the position 25 is subjected to a substitution mutation into lysine, arginine, histidine or tryptophan; the position 29 is subjected to a substitution mutation into alanine, leucine or threonine; the position 49 is subjected to a substitution mutation into arginine or histidine; and the position 58 is subjected to a substitution mutation into glycine, isoleucine or alanine; or (2) a polypeptide having at least 80% of sequence identity to the polypeptide in (1) and retaining substitution mutation in at least one position selected from the group consisting of positions 16, 25, 29, 49 and 58; the polypeptide has high alkali tolerance and high loading capacity.