The invention provides a troilite synthesis method and synthesis device. The method includes the steps: (1) performing ultrasonic treatment on nano-scale zero-valent iron to obtain modified nano-scale zero-valent iron; (2) completely removing air in the device before reaction; (3) controlling the temperature of a reaction system to range from 300 DEG C to 400 DEG C; (4) enabling hydrogen sulfide, nitrogen and carbon monoxide mixed gas to pass the nano-scale zero-valent iron, controlling the volume space velocity of the mixed gas for the modified nano-scale zero-valent iron to range from 200h<1> to 2000h<1>; (5) saturating reaction to obtain troilite. The troilite synthesis method has the advantages of simple process, mild reaction conditions, low energy consumption, omission of high temperature and the like.