This study evaluates the hydrolysis specificity of newly developed protease from Exiguobacterium sp. SWJS2 (EP) based on the released free amino acid (FAA) during enzymolysis and through comparing with commercially available papain and Alcalase 2.4L. Results showed that EP had great potential in producing hydrolysates with better nutrition and less bitterness. The percentages of essential amino acids in the EP-treated Coilia mystus and soybean protein were 72 and 70 %, respectively. And, corresponding hydrophobic amino acids were 74 and 72 %, respectively (i.e. <60 % for papain- or Alcalase 2.4L-treated samples). The differences in FAA releasing rates between EP and the two commercial proteases suggested that EP could become a new commercial protease that offers different reaction rates and extends protease application scope. Track changes in FAA profiles throughout EP hydrolysis revealed that the release of each amino acid exhibited its distinct regularity as the hydrolysis proceeded, which also varied with the substrate proteins. EP hydrolysis of C. mystus and soybean protein led to greater production rates of Phe, Leu, Val, Ile and Ala, suggesting that EP might have higher preference to these amino acids.