P-regular semigroups are an important class of semigroups. Sen described the congruence on a P-regular semigroup by means of a P-kernel normal system. In this paper we consider the additive P-regular semiring and discuss the P-kernel normal system of the additive P-regular semiring. We prove that every congruence on this kind of semiring can induce a P-kernel normal system, and every P-kernel normal system uniquely determines a congruence. In the end we illustrate a P-kernel normal system of an additive P-regular semiring whose +C-set is a semi-ideal.