Two different fillet weld connections and weld throat in tension and shear were tested under dynamic tensile load to study the influence of stress state under impact load on the failure mode, fracture angle and ultimate strength of fillet weld. Compared with the mechanical properties under a static load, the ultimate tension and shear strength increase significantly under a dynamic impact load, which shows obvious strain-rate effect. The dynamic fracture angles of the tensile fillet welds are 45°, which is quite different with static test results. The stain-rate effect of tension fillet weld is more apparent than that of shear fillet weld, and the influence of dynamic increase factor on ultimate strength of fillet weld is in accordance with test results of previous literatures.