Provided is an antimicrobial peptide Sparamosin from Scylla paramamosain. The Sparamosin mature peptide and its functional domain Sparamosin26-54 were synthesized by solid-phase synthesis with a purity of over 95%. Both Sparamosin and Sparamosin26-54 exhibit strong antimicrobial activity. More importantly, Sparamosin26-54 has strong antifungal activity and could inhibit the growth of a variety of yeasts and filamentous fungi. Based on the potent antimicrobial activities of Sparamosin and Sparamosin26-54, both peptides could be developed as alternatives for conventional antibiotics, antimicrobial agents, feed additives in aquaculture and livestock, preservatives, and mold inhibitors.