Abstract: The present paper deals with the initiation of endosperm callus of apple and the ploidy on callus cells through subcultures. According to our observations, the low capacity of differentiation has been discussed. The following conclusions are drawn: 1. The callus initiaed at 2–5 layer cells beneath epidermis. Some cells in this region changed into initials of endosperm callus and from initial masses then develop into cellular masses of endosperm callus protruding on the endosperm surface. The differentiation and growth of callus masses through subcultures may carry out in embryonal and transitional cellular masses in the peripheral zone and basal zone. 2. The ploidy in callus cells is very unstable. Through repeated subcultures the ploidy of the callus cells vary greatly. Most cells (about 80%) contain polyploid and a large number of aneuploid neuclei, while the triploid cells only constitute the minority (about 2.5%–3%). Hence the ploidy in callus cells produced by well developed endosperm vary greatly. 3. It is highly probable that the above mentioned variation of ploidy in callus cells of endosperm, particularly within the embryonal and transitional cellular masses is the cause of the low capacity of differentiation.