Newton's second law aids us in predicting the location of a classical object after knowing its initial position and velocity together with the force it experiences at any time, which can be seen as a process of continuous iteration. When it comes to discrete problems, e.g. building Bell inequalities, as a vital tool to study the powerful nonlocal correlations in quantum information processing. Unless having known precisely the genereal formula of associated inequalities, iterative formulas build a bridge from simple examples to all elements in the set of Bell inequalities. Although exhaust all entities in the set, even in the subset of tight individuals, is a NP hard problem, it is possible to find out the evolution law of Bell inequalities from few-body, limited-setting and low-dimension situations to arbitrary (n, k, d) constructions, i.e. n particles, k measurements per particle, and d outcomes per measurement. In this work, via observing Śliwa's 46 tight (3,2,2) Bell inequalities [Phys. Lett. A. 317, 165-168 (2003)], uniting the "root" method [Phys. Rev. A. 79, 012115, (2009)] and the idea of degeneration, we discover an iterative formula of Bell inequalities containing all (n, k, 2) circumstances, which paves a potential way to study the current Bell inequalities in terms of iterative relations combining "root" method on the one hand, and explore more interesting inequalities on the other.