Abstract: Several factors influencing synthesis and accumulation of ginseng saponin in callus are studied. The abilities of synthesis of ginseng saponin in callus from different explants are same basically. Synthesis and accumulation of ginseng saponin are on a par with the increase of weight of callus. The content of ginseng saponin in cultures is the highest at 0.5-1.0mg/L 2,4-D. The illumination at 2 000 lx is the most favourable for synthesis and accumulation of ginseng saponin. Free 2,4-D clone is induced by subsequent culture accompanied by reducing 2,4-D concentration gradually. Free 2,4-D clone can synthesize and accumulate ginseng saponin at a lower level, and the ability in synthesis and accumulation of saponin can be raised again up-to original level in medium contained 2,4-D.