Provided are chondrosulfatase and a use thereof, belonging to the technical field of biological engineering. Chondrosulfatase is screened and identified from the natural world, the maximum similarity between its amino acid sequence and that of the chondrosulfatase reported by NCBI being 85%; then the expression in Escherichia coli and Bacillus subtilis is optimized, achieving the high-efficiency biosynthesis of chondrosulfatase having high enzymatic activity, the maximum enzyme activity being 11976.5 U/L; furthermore, the entire process and post-processing are simpler. The invention has potentially broad value in application in the preparation of products containing low molecular-weight chondroitin sulfate in the fields of medicine, cosmetics, and biology, lays the foundation for efficient fermentation of a microbial system to produce a chondrosulfatase having high enzyme activity, and is suitable for industrialized production applications.