The present invention belongs to the cotton genetic engineering technical field, in particular to a new method for separating the chloroplast DNA of cotton. The present invention includes: young and tender leaves are taken as material, and are fully homogenated by a common domestic juicer, four kinds of buffer solutions of A, B, C, and D are utilized, the leaves are centrifuged at a general velocity, and the cotton chloroplast DNA pure can be finally obtained successively by the separating and the cracking of the chloroplast as well as the separating and the purifying of the chloroplast DNA (cpDNA). The quality of the chloroplast DNA prepared and separated by the present invention is higher, and the UV spectrophotometer measuring shows that the D260 nm/D280 nm of a DNA sample prepared by the present invention is set between 1.6 and 1.8; the leaf sample yields up to 1-10 microgram cpDNA per gram. After being verified, taking the separated cpDNA as the template can completely satisfy the common molecular biological operation needs such as the specific enzyme restriction, the RAPD, the PCR, the clone of target gene sequences, and so on. Compared with the prior art, the present invention does not need a hypervelocity centrifugal machine, and equipments and steps of centrifugalization through the sucrose density gradient are also not needed.