Abstract: The paper discusses the probability distributions and PH expressions of the discrete time till killing a target. Under the hypothesis that the time between rounds fired follows a discrete PH distribution, it deduces the discrete PH expressions and distributions of the time till killing a target in two situations, considering and not considering the factor of finding the target. Also it gives an example to illustrate the methods for solving the PH distribution and the average value of the discrete time till killing the target.