As Daqing Oilfield is developing oil layer with a big potential,the requirement for the quality of well cementation is higher than ever before.Cement rock is a brittle material containing a great number of microcracks and defects.In order to reduce the damage to cement ring and improve sealed cementing property at the interface,it is necessary to conduct research on the modification of the cement rock available.According to the principle of super mixed composite materials,various fillers are added to the ingredients of cement rock.Dynamic fracture toughness of cement rock will be changed under the influence of filler.In this paper,short rod specimens of cement rock are employed in the experiments to investigate the dynamic fracture toughness of cement rocks with different ingredients using split Hopkinson Pressure Bar,and partial experimental results are given.The results indicate that fiber reinforcement is an effective way to improve the impact resistance of cement rock.