The invention aims at providing RNA type sample preservation and dilution liquid and a preparation method thereof and belongs to the scopes of dilution and preservation of ribonucleic acid (RNA) type samples in the technical field of polymerase chain reactions (PCR). The preparation method comprises the steps of adding a certain amount of RNA preservative and chemical reagent to deionized purified water; adjusting pH value to 4.8-5.2, and then maintaining the constant volume; conducting sealing and autoclaved sterilization, and leaving the mixture for standby application at the room temperature. The RNA type sample preservation and dilution liquid is a white transparent solution, has the advantages of being stable, easy to preserve, convenient and the like and is applicable to preservation and/or dilution of RNA type samples such as serum, plasma, tissues, urine and secreta. After the RNA samples are immersed in the RNA type sample dilution and preservation liquid, RNA in fresh histocyte can be preserved in a good condition for one day at the temperature of 37 DEG C, a week at the temperature of 25 DEG C, one month at the temperature of 4 DEG C and a long time at the temperature of minus 20 DEG C or minus 80 DEG C.