Non‐isothermal crystallization kinetics and dynamics of polymer blends are important to both theory and applications. In this work, we studied the morphology, crystal structure, non‐isothermal crystallization kinetics and dynamics of high density polyethylene/butyl rubber (HDPE/IIR) blends. The non‐isothermal crystallization kinetics is analyzed by Mo's model and the dynamics behavior is analyzed by a linear method. The results of morphology, non‐isothermal crystallization kinetics and dynamics show that the condensed structure of HDPE/IIR blends has a marked influence on their non‐isothermal crystallization kinetics and segmental dynamics. © 2015 Society of Chemical Industry