The invention relates to a recombinant nucleic acid molecule for transcribing circular RNA and application of the recombinant nucleic acid molecule in protein expression. Specifically, the invention relates to the recombinant nucleic acid molecule for transcribing circular RNA, a recombinant expression vector, linear RNA, circular RNA, a recombinant host cell, a pharmaceutical composition and a method for preparing protein. The recombinant nucleic acid molecule is transcribed to form circular RNA containing a specific IRES element, the IRES element can improve the protein expression level of the circular RNA in eukaryotic cells, efficient and durable expression of protein is achieved, and the recombinant nucleic acid molecule has important application values for preparing mRNA infectious disease vaccines, therapeutic mRNA tumor vaccines and mRNA-based dendritic cell tumor vaccines, and in the fields of gene therapy based on mRNA, chimeric antigen receptor T cell therapy based on mRNA,protein supplement therapy and the like.