To study the effects of the pre-existing flaws on dynamic mechanical property of frozen clay, the frozen clay specimens with different flaw positions, flaw numbers, flaw lengths, and angles are tested using a system of split Hopkinson pressure bar (SHPB) with the diameter of 50 mm. Experimental results show that the deterioration degree of pre-existing flaws at side surface on dynamic strength and elasticity modulus are larger than that at end surface of specimen, and the dynamic strength and elasticity modulus of artificial frozen clay specimen show the minimum values with flaw angle of 0° at side surface. Additionally, elasticity modulus of artificial frozen clay decreases with the increase of flaw numbers. Meanwhile, there has a larger growth value about strength deterioration factor when the end surface flaw number increases from one to two, while at side surface of specimen is not obvious. The capability of artificial frozen clay to resist deformation and destruction under dynamic impact load decreases with the increase of flaw lengths, the strength deterioration factor and reduce value of elasticity modulus are 0.472%,7.97%,22.22% at 8mm、12mm and 16 mm flaw length, and the correspond decrease value are 3.59%,15.69%,44.77%, respectively.