The invention discloses a preparation method of shape-controlled silver sulfide. The preparation method comprises the following steps of (1) mixing sulfur-containing amino acid, a silver source and a dispersing agent to obtain a mixed solution; (2) controlling the concentration of silver ions in the mixed solution to range from 0.001 to 0.5mol / L, the adding quantity of the sulfur-containing amino acid to be 0.5 to 2 times the amount of substance of the silver ions in the silver source, the adding quantity of the dispersing agent to be 0.2 to 2 times the mass of the silver source, and a pH (Potential Of Hydrogen) value of the mixed solution to range from 9 to 11; (3) then reacting the mixed solution for 4 to 12 hours at the temperature of 120 to 200 DEG C, and finally centrifuging, washing and drying a product obtained through reaction so as to obtain the shape-controlled silver sulfide. According to the preparation method of the shape-controlled silver sulfide provided by the invention, the sulfur-containing amino acid is adopted as a sulfur source, so that the release speed of sulfur during a reaction process can be effectively controlled, and the shape and the particle size of the silver sulfide are regulated favorably; meanwhile, compared with other sulfur sources, the sulfur-containing amino acid has the advantage of less pollution, and is more green and environmentally friendly.