Sequences of allosteric proteins were designed by evolution so that their energy landscapes are shaped to optimize both folding and allosteric motion.Such additional allostery requirement inevitably introduces frustrations to folding itself.On the other hand, binding of cofactors can further reshape the energy landscape, therefore affects the folding processes.In this work, by constructing a computational model which can integrate folding, ligand binding,and allosteric motions, we study the folding of calmodulin (CaM).Our results revealed tight coupling among CaM folding, allosteric motion, and calcium binding, which leads to multi-route folding/binding pathways.Due to the tight coupling, the folding/binding mechanisms of CaM can be modulated by calcium concentration and by applying mechanical force.