The invention discloses a phosphating solution for an electrostatic powder sprayed metal part. The phosphating solution is prepared from the following components in parts by weight: 1000 parts of magnetized water, 3-5 parts of magnesium oxide, 4-6 parts of zinc oxide, 3-5 parts of phosphoric acid, 0.5-1 part of silver nitride, 3-5 parts of potassium fluoride, 1.5-2.5 parts of nanometer silicon dioxide, 1-2 parts of nanometer boron fibers, 4-6 parts of modified starch, 1-1.5 parts of an antifreezing fluid of an automobile, 0.4-0.6 part of catechin, 2-4 parts of cyclohexanone, 1-1.5 parts of lotus leaf ash, 4-6 parts of dodecylthiol and 1.5-2.5 parts of tartaric acid. A preparation method of the phosphating solution comprises the steps of delivering all the components into a reaction kettle, heating to 90+5 DEG C, continuously stirring for 50min at the stirring speed of 200r/min, preserving the heat for 1h, and taking a product out of the kettle. When the phosphating solution is used, the phosphating temperature is 80-85 DEG C, and the treatment time is 30-35min.