Plant tissue culture systems have enormous potential in fundamental re- search and for commercial applications such as horticultural industry. The process of tissue culture is companied with a series of changes in respect to morphology, physiology, biochemistry, molecule and epigenetics. The changes at molecule levels mainly include genetic variation, DNA sequence variation, chromosomal variation and epigenetic regulation （DNA methylation, histone modification, chromatin remodeling, small RNA regulation）. These changes are believed to facilitate explant adaptation to culture conditions and to help subsequent morphogenesis processes. Nowadays, it has played a crucial part in commercial applications and in basic research into cell biology, genetics and biochemistry, etc. In present review, we shed light on the fun- damental of plant tissue culture, culture medium preparation, explant selection, mechanism of action of various hormones, the three major problems （explant pollu- tion, browning, plantlets vitrification） and the prevention measures in tissue culture, and elaborated on in vitro propagation of plants, virus-free seedling cultivation, cry- opreservation, artificial seeds and molecule levels changes during in vitro culture further.
