Abstract: Daminozide (B9), chlormequat chloride (CCC), paclobutrazol (PP333), and abscisic acid (ABA) were supplied in culture media during subculture process in apple cultivars of Fuji, Jonagold, Goldspur, and Gala in order to study the efficacy of plant growth regulators on slow growth of apples in vitro for germplasm conservation. The results showed that B9 and CCC could significantly retard the growth of plantlets with a high surviving rate and healthy growth status, and the plantlets could resume their growth immediately after transferred onto routine subculture medium. The optimal concentration for B9 was 80mg/L and for CCC was about 75mg/L, which could be used in apple germplasm conservation in vitro. CCC could also significantly retard the growth of plantlets, but that could cause vitrification in some cultivars, so its application was selective with caution. ABA had a very strong effect and could result in death for most of the plantlets, and then its application was not suggested in apple germplasm conservation in vitro.