The invention discloses a method and a special culture medium for subculturing chicken embryonic stem cells for a long time. The method is characterized by comprising the following steps of: isolating cells of area pellucida of X-stage blastoderm, dispersing into single cells or small cell masses through mechanical blowing and beating, inoculating on an STO feeder layer, culturing the chicken embryonic stem cells in the special culture medium at the temperature of between 37 and 38 DEG C, and subculturing once every 3 to 5 days, wherein the special culture medium comprises 600 to 900mL of conditioned medium, 50 to 150mL of fetal calf serum, 5 to 20mL of chicken serum, 5 to 25mL of one or a mixture of more of non-essential amino acids, 0.146 to 0.292g of L-glutamine, 6 to 14mu L of beta-mercaptoethanol, 1 to 2*10<6> IU of mouse leukemia inhibitory factor, 10 to 50mu g of alkaline fibroblastic growth factor and 5 to 20mu g of stem cell growth factor; and fixing the volume of the ingredients to 1,000mL by using a dulbecco's modified eagle medium (DMEM) (high glucose), and regulating the pH value to 7.2 to 7.5. The conditioned medium is obtained by the steps of: culturing BRL-3A cells until the cells are converged, collecting supernatant of the cultured cells, performing centrifugal separation, and filtering by using a filter membrane to obtain the conditioned medium. Compared with the prior art, the method has the advantages that: the long-term subculture of the chicken embryonic stem cells can be realized, the proliferation of the cells is quick, and the cloning yield is high.