The invention discloses a method for simultaneously extracting 
DNA (deoxyribonucleic acid) and 
RNA from lily tissue. The method comprises the following steps of: obtaining total 
nucleic acid solution through crude extraction and purification of the same steps from a lily 
tissue sample; and then sequentially selectively precipitating 
RNA and 
DNA, thereby obtaining high-quality 
DNA and 
RNA. The method disclosed by the invention is short in time, economic and fast, and good in stability; and the extracted 
nucleic acid is high in quality. The method has the characteristics that high-concentration 
potassium acetate is utilized for precipitating polysaccharides twice, so that the polysaccharides in the lily sample can be effectively removed; and in the DNA and RNA 
separation process, the RNA is selectively precipitated by means of the synergistic effect of 
lithium chloride and absolute ethyl 
alcohol and then the DNA is precipitated by using 
sodium acetate and isopropanol; and therefore, the efficiency of the DNA-RNA separation is high, the loss of the 
nucleic acid is low and the 
precipitation time is greatly shortened. The method is suitable for simultaneously extracting the DNA and the RNA from the lily tissue containing rich polysaccharides and other secondary metabolites.