In this study, we try to apply the existing degradation-shock process to each unit and combine it with a mathematical model for reliability evaluation of a parallel system. Assuming that the time interval between external shocks follows a Poisson process and that the rapid deterioration due to a single shock follows a normal distribution, the total deterioration of a unit includes continuous deterioration and cumulative rapid deterioration. Furthermore, when one unit fails, the load it bears is transferred to the adjacent unit, increasing the load on the adjacent unit and accelerating its own degradation rate. We enumerate the component failure sequences leading to system failure in which all components fails, and a formula for calculating the reliability of the whole system is derived.