In the present work, a physically-based constitutive model is formulated for the stretch-induced crystallization in rubbers. To describe the progressive evolution of the crystallinity degree at the chain-scale, a micro-mechanism inspired molecular chain approach is developed within the framework of the continuum thermodynamics. The transition from chain-scale to macro-scale is realized via the microsphere-based strategy and a quantitative evaluation of the model is performed by comparisons with tensile experiments in terms of hysteretic response induced by the crystallization.