The utility model discloses a strain clamp includes the wedge casing, and this wedge casing includes the wedge base plate and establishes the L shape curb plate in wedge base plate both sides. The vacuole formation between the curb plate and wedge base plate and two L appear. The forefront splint and the second -line splint that are equipped with in this cavity and set up relatively, these forefront splint and second -line splint all slide with the wedge casing and set up. And the utility model discloses a fastening structure is equipped with on the wedge casing, the structure should be fastens with forefront splint and the fastening of wedge casing, also with second -line splint and the fastening of wedge casing. The fastening structure can with the clamp tightly support to lean on the inner wall at the wedge casing on, consequently the utility model discloses a when strain clamp uses, can resist blowing of nature and move, can prevent forefront splint and second -line splint to be taken out from the cavity, just also prevent the power transmission line that it pressed from both sides to be taken out to the condition of having avoided moving the short circuit between the power transmission line because of blowing takes place, has guaranteed the safety of transmission of electricity.