The invention relates to the technical field of natural rubber primary processing, and in particular relates to an ammonia-free preservative for natural fresh latex. An oxidation-type bactericide is selected from a large amount of solid, water-soluble, non-volatile and broad-spectrum bactericides aiming at pollution problems of ammonia and ammonia composite preservatives, and the oxidation-type bactericide is compounded with an alkaline stabilizer to be used as a preservation system of the natural latex. The novel preservation system provided by the invention has the characteristics of a goodpreservation effect, low costs, no ammonia, no volatilization, no irritation, easy solubility in water and convenient use, and can preserve the natural latex for a plurality of days, and the preparedraw rubber has excellent properties, especially has significantly-improved aging resistance; and in addition, the preservative can also be applied to early-stage preservation in the ammonia-free concentrated latex preparation process, and the overall costs are lower than those of a currently-used ammonia and TT/ZnO systems.