The strength development of cold regeneration with asphalt emulsion（CRAE） under the constant environment condition was revealed by indoor simulation test， and then the strength contribution in different periods under the conditions of different content of cement and asphalt emulsion was studied. The cement hydration process in cement emulsified asphalt mortar， and asphalt emulsion demulsification process were analyzed by micro analysis method such as ESEM et al. The results indicate that the development of strength of CRAE shows the long term mode that not only the rapid growth in the early stage and the slow growth in the late stage, but also the early and late strength can be promoted significantly by cement. It has also shown that the larger the content， the higher the amplitude； cement contributes to the rapid improvement of early strength. Demulsification asphalt provides the main source of strength. At the best asphalt emulsion content maximum early or late strength can be achieved. The early cement hydration reaction can be inhibited by asphalt emulsion and the effect of cement on asphalt emulsion demulsification is mainly reflected by the attraction of cement particles and the particles agglomeration due to the hydration product. The reinforced structure formed by cement hydration products and asphalt can promote the strength further.