The invention discloses a pressure reducing valve preparation method, and belongs to the technical field of pressure reducing valve manufacturing. The method comprises the following steps: (a) a valve body of a pressure reducing valve comprises the following chemical components in percentage by weight: 0.13-0.18% of C, 0.3-0.4% of Si, 0.7-0.9% of Mn, 0.01-0.02% of P, 0.01-0.02% of S, 1.8-2.2% of Cr, 1.0-1.2% of Mo, and the balance of iron; (b) casting liquid is injected in a mold for cooling solidification to obtain the valve body; (c) the valve body is preheated to 200-250 DEG C in a heating furnace, and is put in the heating furnace; the temperature in the heating furnace is increased at 70-90 DEG C/h; when the temperature is increased to 370-400 DEG C, the temperature is kept by 3 h; when the temperature is increased to 450-500 DEG C, the temperature is kept by 3 h; and when the temperature is increased to 550-580 DEG C, the temperature is kept by 5 h; (d) the valve body is cooled to the room temperature; (e) the valve body is clamped on a lathe for rough machining and finish machining; (f) a sealing end surface of the valve body is grinded and polished; and (g) anti-corrosion paint is sprayed on the surface of the valve body. The manufactured pressure reducing valve is excellent in mechanical performance, cannot generate cracks, and is excellent in sealing performance.