The present invention discloses a blood cell analyzer reagent, which comprises at least an alkali metal salt having reducing ability, at least a buffering agent and at least an alkali metal salt. According to the present invention, the reagent can be used as the sheath flow dilution liquid of the blood cell analyzer, wherein the dissolved oxygen content in the reagent can be effectively reduced so as to reduce the dissolved gas release caused during the storage and transportation process and ensure the stability of the instrument background; and with the reagent, the appropriate pH value, the conductivity and the osmotic pressure can be provided for the detected sample of the blood cell analyzer, the morphology integrity of the sample cell can be ensured, and the hemolysis does not occur. The invention further discloses a production process of the reagent.