Ribonuclease (RNase) is a class of nucleases that catalyzes the degradation of RNA into small fragments. The RNase family includes RNaseA, RNaseB, RNaseC, RNaseH, S-RNase, RNaseP, RNaseT, etc. Among them, RnaseA is a widely used endonuclidenase. RNaseA efficiently and specifically catalyzes the break of phosphodiester bonds on the single-stranded RNA skeleton at the 3' end of pyrimidine nucleotide residues C and U to form oligonucleotides with 2', 3' -cyclic phosphate derivatives. At present, the common RNase residue detection methods mainly include radioisotope method, spectrophotometry, fluorescence quenching method and electrochemical method. The RNase residue quantitative detection kit provided by Solarbio is a rapid and highly sensitive detection kit for RNaseA activity by fluorescence method with high sensitivity and the lowest detection limit as low as 0.078pg RNase. The substrate is a synthetic RNA oligonucleotide probe with a FAM Fluorophore (Donor) at one end and a TAMRA Quencher (Acceptor) at the other end. The absorption spectra of the two groups overlap to a certain extent, and when the distance between the two fluorophores is appropriate, the fluorescence energy is transferred from the donor to the acceptor, resulting in the fluorescence intensity of the donor fluorescence molecule itself decays. When the substrate was cut by RNase, the end and end of the substrate were separated, the two groups were separated, the fluorescence of FAM was no longer damped by TAMRA, and the fluorescence of FAM could be detected. The increase rate of the fluorescence signal was positively correlated with the amount and activity of the enzyme.