In the invention, the minimum inhibitory concentrations of human-originated EGF domain proteins against different Gram-negative bacteria are detected with the in vitro antibacterial activity. It has been shown that the human-originated EGF domain proteins have an obvious inhibitory effect on the Gram-negative bacteria, so as to develop a novel class of medicaments for treating Gram-negative bacteria infection. It has been demonstrated by silver staining that the human-originated EGF domain proteins have the effect on hydrolyzing and eliminating the endotoxin, which facilitates the development of a novel class of medicaments for treating endotoxemia. The amino acid sequences of the human-originated EGF domain proteins are the one described in SEQ ID NO: 1 in the sequence listing, or those having homology of over 50% to the amino acid sequence described in SEQ ID NO: 1.