The invention discloses a preparation method of a zinc alloy fire extinguisher valve body, and belongs to the technical field of fire extinguisher valve body preparation. The preparation method includes the steps that a zinc alloy bar is cut into a small section at first and then is put into heating equipment to be subjected to heating and thermal insulation, and the lead content in the zinc alloy bar is lower than 0.1%; the prepared zinc alloy blank bar is fed into a machining station, stamping equipment is started for punch forming, and the zinc alloy bar is machined into a valve body crude product; after the valve body is machined, a machined mounting hole is subjected to deburring, an internal thread of the valve body is wasted, thread burrs are removed, and an inner hole of the valve body is subjected to ultra-precision extrusion so that the roughness can be improved; and the obtained valve body is subjected to ultrasonic cleaning, and accordingly a fire extinguisher valve body finished product can be prepared. Compared with a copper valve body, the zinc alloy fire extinguisher valve body prepared through the method is low in cost, and corrosion by a fire extinguishing agent can be well prevented. Compared with an aluminum alloy valve body, no surface anodic polarization treatment is required, continuous washing with water in the machining process is needless, the machining speed can be increased, equipment investment can be reduced and energy consumption is low.