The invention discloses an antibacterial active part of a cockroach, and an extraction method and use thereof. Researches in the invention unexpectedly find that a petroleum ether extraction part of the cockroach has good inhibitory activity to both tested gram-positive bacterium and gram-negative bacterium; furthermore, the activity of the petroleum ether extraction part of the cockroach is obviously prior to that of an ethyl acetate extraction part; and an n-butyl alcohol extraction part and a 95% v/v ethanol extraction part do not have obvious antibacterial activity.