The invention relates to the technical field of a plunger pump, and particularly relates to a preparation method of a chemical material slurry plunger pump with composite coating, and a product thereof. The preparation method comprises the following preparation steps: performing undercutting for a part where coating of a plunger base body is, thereby reserving 0.25-0.35mm coating thickness, chamfering 40-50 degrees for a connection part between a coating edge and the base body; executing organic solvent degreasing and baking for the base body; then, performing sand blasting, using a clamp forprotecting a non-coating area; preheating the base body to 90-110 DEG C, spraying a nickel chrome bottom layer coating, wherein spraying current is 350-450A, voltage is 35-40V, and coating thickness is 0.08-0.12mm; spraying a chromic oxide coating, wherein spraying current is 500-600A, voltage is 40-50V, and coating thickness is 0.2-0.4mm; performing vacuum impregnation hole sealing, wherein impregnation time is 10-20 minutes, heating curing is executed after surface drying, and curing time is 1.5-2.5 hours; and using a grinding machine to perform grinding processing for the plunger, wherein grinding processing comprises three working procedures including coarse grinding, fine grinding and polishing. The chemical material slurry plunger pump with composite coating, prepared by the method of the invention has high corrosion resistance and abrasion resistance.