Uncertainty is probably one of the characteristic features causing stress today. This paper discusses thoughts and research on the relationship between uncertainty and stress. Given that both concepts are ambiguous and uncertain, this paper proves that uncertainty is a main feature of complex systems. However, considering that the interaction between a person and their job is a complex system, hence a source of uncertainty and stress. The correlation between uncertainty and stress, the origins of uncertainty, and finally, the relation between uncertainty and the nature of coping strategies are successively discussed.