The present invention relates to a mixed saccharide electrolyte injection preparation method, which specifically comprises: 1) adding water for injection to a concentration preparation tank, opening stirring, sequentially pouring sodium hydrogen sulfite, glucose, fructose, xylitol, magnesium chloride, calcium chloride, sodium chloride, sodium acetate and zinc sulfate, stirring, adding citric acid, completely stirring, adding dipotassium hydrogen phosphate, carrying out stirring dissolving, adding active carbon, stirring, adsorbing, switching valves, and pumping the drug liquid in the concentration preparation tank into a dilution preparation tank; 2) adding the water for injection to achieve the whole amount, stirring, opening a drug liquid pump to make the drug liquid respectively pass through a 5 [mu]m filtration core, a 0.45 [mu]m filtration core and a reflux pipeline, and filling; and 3) carrying out water bath type sterilization cabinet thermal pressure sterilization for 8-12 min at a temperature of 121 DEG C. According to the present invention, the degradation product 5-HMF of the saccharide in the injection is reduced; the medication safety is ensured; and the production operation is simple, the preparation time is shortened, and the production cost is saved.