The invention relates to a C-type β-glucosidase mutant and its expression plasmid and recombinant bacteria, in particular to a C-type β-glucosidase mutant with significantly improved enzyme activity and a construction method thereof, belonging to biological engineering Technical field; The present invention carries out site-directed mutation on the β-glucosidase derived from Taiwan termites, and changes the lysine K at the 170th position into serine S and tryptophan W respectively, and the phenylalanine F at the 182nd position is methionine M, the amino acid histidine H at the 252nd position becomes asparagine N, and is respectively expressed as Glu1C-K170S, Glu1C-K170W, Glu1C-F182M, Glu1C-H252N; the obtained mutant of the present invention Enzyme activity has improved respectively 5.2 times, 2.05 times, 2.9 times, 2.1 times compared with before mutation; The application of biocatalytic technology provides a favorable basis for industrial application, can better meet the requirements of social production, and has broad market prospects.