Abstract: The quenching behavior of high-temperature superconductor Bi2223/Ag strip cooled at 30-70K under conditions of GM refrigeration was investigated experimentally. A testing setup for quench propagation of superconductor was thus built up with the control procedure programmed by LabVIEW language for the testing system to measure the quench propagation velocities under different operating conditions. The results showed that the quench propagation velocities increase with temperature rise and increasing current, i.e. the higher the temperature and current, the lower the superconductive stability and the easier the formation of quench propagation. Such results are in conformity to that by theoretic analysis.