Abstract: Ac1-FFT (fructan:fructan 1-fructosyltransferase) cloned from Agropyron cristatum was transformed into embryogenic callus lines of Lolium perenne using an Agrobacterium mediated method. Transgenic plants were analyzed by basta spraying and PCR amplification. In total, 18 independent transgenic lines were obtained with significantly improved drought tolerance. RT-PCR analysis showed that Ac1-FFT expressed strongly in transgenic L. perenne plants but not in control plants. Water soluble carbohydrate and fructan contents of Ac1-FFT transgenic L. perenne were significantly higher than those in control plants. Relative water content and chlorophyll content were significantly higher, while electrolyte leakage and malondialdehyde (MDA) content were significantly lower in the Ac1-FFT transgenic L. perenne than in control plants for 6 days after drought treatment. Relative water content, chlorophyll content, electrolyte leakage and MDA content were restored to their original levels after rewatering in Ac1-FFT transgenic plants but not in control plants. This suggests that the damage to Ac1-FFT transgenic plants was reversible but it was not in control plants. Ac1-FFT expression and fructan biosynthesis may play an important role in improving drought tolerance of Ac1-FFT transgenic L. perenne.