Two tasks are attempted in this article. First, a stochastic model of change and continuity in a nation's diplomatic principles is established. Second, the model is applied to mainland Chinese diplomacy. The Chinese mainland is selected due to the tumultuous changes in its diplomacy over the past thirty-seven years. Indeed, the findings reinforce the notion that its foreign policy can be regarded as unstable. Other characteristics of its foreign policy include the necessity of balance between domestic political factions and how a significant portion of the Chinese population is not associated with any particular faction yet is ready to change sides during uncertainty.