The invention discloses an expression system for enhancing the production and preparation of silk proteins. The expression system contains a coding sequence and mutant tRNA of the protein. The proteincan be the silk protein with a sequence of SEQ ID NO. 8, and the sequence of the mutant tRNA is shown by SEQ ID NO. 18. The silk protein expressed by the expression system is excellent in mechanicalproperties. The expression system of the invention is beneficial for enhancing the expression of the silk proteins and good for manufacturing a silk protein fiber material. The mutant tRNA can significantly up adjust the protein containing a plurality of rare codons in a gene coding area in a host cell and can especially improve the expression of the silk protein containing a plurality of rare codons; and the effect is better than the tRNA for naturally identifying the rare codons. On the basis, the invention also provides a method for utilizing the mutant tRNA of the invention to up adjust the expression of the protein in the host cell.