As major projects such as nuclear power plants continuously increase, it is inevitable that loopholes will arise in safety precautions. Airplane anchoring structures, comprising steel joints and acting as a key component of such a major project, directly affect the safety of the project due to their resistance to the instant impact of an airplane. Existing impact testing machines have the limitations of being unable to balance impact velocity and impact force, as well as having inadequate control of impact velocity; they cannot meet the requirements of impact testing for steel mechanical connections in nuclear power plants. This paper discusses the hydraulic-based principle of the impact test system, adopts the hydraulic control mode, and uses the accumulator as the power source to develop an instant loading test system suitable for the entire series of steel joints and small-scale cable impact tests. The system is equipped with a 2000 kN static-pressure-supported high-speed servo linear actuator, a 2 × 22 kW oil pump motor group, a 2.2 kW high-pressure oil pump motor group, and a 9000 L/min nitrogen-charging accumulator group, which can test the impact of large-tonnage instant tensile loading. The maximum impact force of the system is 2000 kN, and the maximum impact rate is 1.5 m/s. Through the impact testing of mechanical connecting components using the developed impact test system, it was found that the strain rate of the specimen before failure was not less than 1 s−1, meeting the requirements of the technical specifications for nuclear power plants. By adjusting the working pressure of the accumulator group, the impact rate could be controlled effectively, thus providing a strong experimental platform for research in the field of engineering for preventing emergencies.