The impact toughness of EN-GJS-400-18-LT ductile iron was measured by Charpy V-notch impact test at temperature between-80 and 20℃.The fracture properties were tested under instrumented impact loading.Total impact fracture energy,crack initiation and propagation energy,dynamic loads and the ductile to brittle temperature were measured.Three-dimensional reconstruction of impact fracture morphology was accomplished by confocal laser scanning microscope.The results of quantitative fractography indicate that cleavage fracture produces flatter fracture surfaces accompanying with less absorbed energy during the impact fracture process.It indicates that fracture roughness has a close relationship with crack propagation energy at low temperature. The impact toughness of EN-GJS-400-18-LT ductile iron was measured by Charpy V-notch impact test at a temperature between -80 and 20 ° C. The fracture properties were tested under instrumented impact loading. Total impact fracture energy, crack initiation and propagation energy, dynamic loads and the ductile to brittle temperature were measured. Three-dimensional reconstruction of impact fracture morphology was accomplished by confocal laser scanning microscope. The results of quantitative fractography indicate that cleavage fracture produces flatter fracture surfaces accompanying with less absorbed energy during the impact fracture process .It indicates that fracture roughness has a close relationship with crack propagation energy at low temperature.