Abstract:Lilium ‘Starfighter’and‘Tiber’are treated with colchicines in vitro, the tetraploid population of the two varieties are obtained. ‘Hongyun 3’and ‘Hongyun 5’are selected from the tetraploid population. The tetraploid varieties are better than its diploid varieties in major characteristics. Strong adaptability to cold, and easy propagation, both of two new varieties are good cut-flowers.