Abstract: In formalization of rational agents, the common idea is to consider agents whose mental state comprises the three attitudes of belief, desire, and intention. While the static relationships among these entities has received considerable attention, but the manner in which these entities change over time has not been studied well. In this paper, some problems are examined, which exist in the intuitive semantics of intention maintenance, and a dynamic model of intention maintenance in the context of changing beliefs and desires is provided. Comparing with Rao and Georgeff’s model of intention maintenance, the model is more general and simple. It does not need to specify the temporal structure of possible worlds and does not need to introduce forms for only modalities of belief, desire, and intention. Also there do not exist the logical omniscience problem and the side-effect problem under tautological implications for desire and intention.