Elastocaloric cooling technology is a novel solid-state cooling technology based on the latent heat associated with martensitic phase transformation in shape memory alloys. The active elastocaloric regenerator concept was recently demonstrated as a promising approach for this technology. However, if not properly designed, the large temperature gradient in the active regenerators could lead to significant degradation of elastocaloric effect and system performance. To address this challenge, a numerical model was developed in this study with phase transformation kinetics of shape memory alloys, which is capable to investigate the stress-induced or temperature-induced phase change phenomena and elastocaloric effect degradation problem. The performance of an elastocaloric cooling system with a pair of active regenerators is studied in terms of operating frequency, flow rate, geometric parameters and thermal conductivity of the material. Most importantly, the condition to avoid eCE degradation was found as the matching principle to guide material selection for future studies. (C) 2017 Elsevier Ltd. All rights reserved.