<p>This study investigated the dynamic tensile mechanical behavior of he CrMnFeCoNi high-entropy alloy (HEA) at elevated temperatures. An assembly system was constructed based on the electromagnetic split Hopkinson tensile bar (ESHTB) to achieve synchronous high-temperature dynamic tensile loading, ensuring the accuracy and reliability of the test data. High-temperature quasi-static tensile tests were also conducted for comparison. Additionally, an optimized specimen suitable for high-temperature dynamic tensile loading was designed, and finite element methods confirmed that the specimen met the loading requirements. The test results show that the synchronous assembly system can ensure that the cold contact time of the specimen is within 114 ms, significantly reducing the temperature rise at the rod end. In addition, the CrMnFeCoNi HEA exhibits significant strain hardening, strain rate strengthening, and thermal softening effects under dynamic high-temperature tensile loading. Whether under quasi-static or dynamic loading, as the temperature rises, the alloy shows a tendency to shift from ductile to brittle fracture. In the temperature range of 20 to 400 °C, the cooperative deformation of dislocations and twins is the primary deformation mechanism. As the temperature increases, the dynamic recovery (DRV) mechanism is enhanced, leading to a decrease in flow stress. At 800 °C, due to limitations of the critical recrystallization temperature and high strain rate, dynamic recrystallization is suppressed, and DRV remains the predominant deformation mechanism.</p>