For the application of HTS composite conductor to electric power apparatuses such as power cables or transformers, its stability under a short circuit fault condition is very important. In an actual power system, we have to take into consideration the large short circuit current. Meanwhile, so far, the only available HTS conductor for a practical application seems to be Bi2223/Ag HTS tape. So, we have started a study on a transient behavior of Bi2223/Ag HTS tapes during a short circuit condition in liquid nitrogen under self-magnetic field. In this paper, we have carried out an experiment and a numerical study on a transient of the voltage and the thermal behavior of HTS tape. In the experiment, the current was increased rapidly from a small steady state level to a large level higher than the critical current. We have produced the calculation code that simulates the transient phenomena. The experimental results were compared with the numerical ones.