In this work extension induced crystallization of end-linked polyethylene oxide (PEO) network was investigated with in-situ small angle X-ray scattering (SAXS) and rheological measurement. The coupling between crystallinity and stress of crosslinked network makes the morphology time dependent. With a large strain the structure evolution in the stretched network is found to follow a two-stage process: i) crystals with high numerical density and small dimension form first, which laterally correlate with adjacent ones; ii) continuous melting and fusing of adjacent crystal happen after the first nucleation stage, leading to increase of crystal dimension and stability. Decreasing strain a gradual transformation to normal lamellae formation is found. Strain tuned confinement and crystallization induced confinement release is supposed to induce the structural change. (C) 2013 Elsevier Ltd. All rights reserved.