Abstract: Using the transmission line and drift diffusion coupling model (TLM-DDM), this paper analyzes the damage effect and mechanism of the silicon bipolar transistor induced by the cable under the X-ray pulse. The result shows that the damage effect can be decided by the lattice temperature of the bipolar transistor, and the burnout point appears first near the n-N+ interface above the center of the collector region. The paper also describes the relationships of the damage energy and burnout time with the X-ray pulse width and fluence in the curve fitting. When the pulse width of the X-ray increases, the damage energy is almost unchanged and the burnout time increases gradually. The burnout time reduces as the X-ray fluence increases, and the damage energy increases after the X-ray fluence exceeds 5.86 J/cm2.