The invention relates to a method for rapidly identifying cassava autotetraploid, and belongs to the technical field of autotetraploid identification. The method for rapidly identifying the cassava autotetraploid comprises the following steps: 1) immersing a cassava leaf in a Carnot fixer to obtain a fixed cassava leaf; 2) taking the lower epidermis of the fixed cassava leaf obtained in step 1), and staining the lower epidermis in an iodine-potassium iodide staining solution to obtain a stained lower epidermis; and 3) microscopically observing the stained lower epidermis obtained in step 2), counting the number of chloroplasts in the guard cells, determining the cassava as an autoteraploid if the number of chloroplasts in more than 90% of the guard cells in the visual field is 7 or more, and determining the cassava as a diploid if the number of chloroplasts in more than 90% of the guard cells in the visual field is less than 7. The identification method has the advantages of low cost,high speed, high accuracy, and realization of efficient and rapid detection of the cassava autotetraploid.