Reagent for extracting and purifying DNA

The invention discloses a reagent for extracting and purifying DNA, comprising the following substances: preprocessing lysis solution with pH of 7.4-8.5: water serves as solvent, and solute comprises the substances with the following final concentration: 10-100mM of buffer salt, 0.5%-5% of surface active agent, 1-100mM of chelating agent, 50-150mM of soluble salt, and 0.2-4mg/ml of protease K; pyrolysis combined liquid with pH of 6.4-7.4: water serves as solvent, and solute comprises the substances with the following final concentration: 20-150mM of buffer salt, 3-8 of MChaotropic salt, 1-10% of surface active agent, 0.5-4% of amphoteric ion detergent, 10-100mM of chelating agent and 15-30% of alcohol; cleaning solution I: water serves as solvent, and solute comprises the substances with the following final concentration: 4-6 of MChaotropic salt, 25-50% of alcohol and 10-100mM of chelating agent; cleaning solution II is 75% of ethanol water solution; spent regenerant is TE (10mM Tris-HCl, 1mMEDTA, and pH is 8.0); magnetic bead suspension is nanoscale silicone coated magnetic microsphere (50-100mg/ml).The DNA extracting efficiency is as high as 93.67% by adopting the reagent.