Extraction kit of circulating nucleic acid and extraction method of circulating nucleic acid

The invention relates to the technical field of nucleic acid extraction, and particularly discloses a circulating nucleic acid extraction kit and a circulating nucleic acid extraction method. The circulating nucleic acid extraction kit provided by the invention comprises a lysis enhancer, protease K, a lysis binding solution, a magnetic bead suspension, a deproteinization solution, a rinsing solution and an eluent, the cracking binding solution and the deproteinization solution respectively contain 10-30% (v/v) of alcoholic solution, and the alcoholic solution is selected from one or more of PEG (polyethylene glycol) 400, PEG 600, PEG 800, PEG 1000, PEG 2000, ethylene glycol, 1, 2-propylene glycol, 1, 4-butanediol, glycerol and pentaerythritol. The extraction kit for circulating nucleic acid provided by the invention can enable a biological sample to fully release nucleic acid crosslinked by protein, can effectively remove large-fragment nucleic acid such as genome, and significantly improves the extraction y