With sentences extracted from COCA, this study analyses and summarizes the secondary grammaticalization process of English modality.This article discovers that the secondary grammaticalization process of English modality does not have a single path, but has five paths totally:Deontic-Dynamic-Epistemic, Deontic-Epistemic, Dynamic-Deontic-Epistemic, Dynamic-Epistemic, Modal Auxiliary-Inflectional Tense Marker.They all start with event modality and end up with epistemic modality.The accompanying changing features are subjectification, semantic generalization, and metaphorization.The mechanism of English modality's secondary grammaticalization process is metaphorical transfer from socio-physical domain to speaker's attitude or belief domain, from the context which expresses concrete concept extended to context which expresses abstract concept through analogy and reanalysis.