Background and Purpose: The widespread abuse of antibiotics have led to increasing resistance of many important human pathogens. The urgent need to develop novel antimicrobial therapies has stimulated great interest in antimicrobial peptides as therapeutic candidates for the treatment of infectious diseases. Scorpion venom-derived peptide Androctonus Amoreuxi Antimicrobial Peptide 1 (AamAP1) is a new type of host defense peptide with broad-spectrum but moderate antimicrobial property. Most importantly, AamAp1 has been proved to be highly hemolytic and displays significantly high toxicity against mammalian cells. The aim of this study was to evaluate the antimicrobial activity and mechanism of a novel synthetic antimicrobial peptide GK-19 deriving from AamAP1 and its derivatives. Experimental Approach: Five bacteria and three fungi were used to evaluate the antimicrobial effect of GK-19 in vitro. Mouse models of scalded combined with skin and soft tissue infections were used to evaluate the antimicrobial effect of GK-19 in vivo. Key Results: The results indicated that Gk-19 could not only inhibit Gram-positive and Gram-negative bacterial growth but also kill fungi by permeabilizing microbial membrane. Cellular and in vivo studies proved that GK-19 showed negligible toxicity to mammalian cells, low hemolytic activity and high stability in plasma. Furthermore, in mouse models of scald combined with skin and soft tissue infections induced by either Methicillin-Resistant Staphylococcus Aureus (MRSA) or Candida Albicans, GK-19 showed significant antimicrobial and healing effects. Conclusion and Implications: The novel scorpion venom-derived peptide analogue GK-19 is a promising drug candidate in the battle against multi-resistant bacterial and fungal infections.