The present invention provides a method for preparing retinal ganglion cells, which comprises the following steps of: obtaining a somatic cell; constructing lentiviral particles, transfecting the somatic cell with the lentiviral particles, integrating an Ascl1 gene, a Islet1 gene, and a Brn3b gene into the somatic cell chromosome; and performing induction culture to obtain the retinal ganglion cells. The retinal ganglion cells are obtained by integrating the exogenous Ascl1 gene, the Islet1 gene, and the Brn3b gene into the mouse fibroblast chromosome for overexpression preparation. Compared with the prior art, the present invention creatively selects a combination of the Ascl1 gene, the Brn3b gene and the Islet1 gene, the three transcription factors are overexpressed in the somatic cellsby lentivirus-mediated means, and more than 10% of the somatic cells can be transdifferentiated into Brn3a-positive, Tuj1-positive retinal ganglion cells in 7 days of induction culture, and the efficiency is high.