The invention provides a tag and a method for improving the soluble expression of an enzyme, and designs a tag sequence that can improve the soluble expression of an enzyme. The method includes: connecting a nucleotide sequence of a fusion label to the C-terminus of the original enzyme nucleotide sequence by genetic engineering means, introducing an expression vector, transforming the recombinantexpression vector into a recombinant strain for expression, and increasing the soluble expression of the enzyme by 10-20 times.