The invention provides a lead-carbon gel battery colloidal electrolyte formula and a preparation method thereof. The prepared colloidal electrolyte mother solution has very high stability, can be prepared in advance, and can be stored at 0-40DEG C for more than 6 months. The preparation method is easy and convenient to operate, has no need for premixing, and reduces steps of the production process, has high production efficiency, can achieve instant use after mixing, avoids the problem of treatment of excess colloidal electrolyte in colloidal electrolyte premixing, and is beneficial to environmental protection. Because of small particle size, low concentration, small raw material consumption, low cost, and small resistance, the colloidal electrolyte has good large current discharge performance. The colloidal electrolyte provided by the invention is transformed from liquid phase into solid phase, is not reversible, and the solid phase is stable and reliable.