The aim of this article is to investigate the effects of Nylon nanofiber in carbon- epoxy composites properties under double cantilever beam test by Non-destructive Acoustic Emission testing. In order to increase tougher of carbon- epoxy composite, Nylon nanofibers were placed in to the midplane interface of carbon- epoxy laminates. In order to better identification of the effects of Nylon nanofibers and more accurate clustering of Acoustic emission parameters were used combining of k-means algorithm and Genetic algorithm for clustering. Acoustic emission descriptors like Amplitude, Duration, Count, Acoustic Energy and Rise time were used in order to survey identification of effects of nanofibers. The results of clustering of Acoustic emission signals that obtained from carbon- epoxy composite and carbon- epoxy nanomodified composite shows that the presence of Nylon nanofibers increase the tougher of carbon- epoxy composite and delayed damage mechanisms. This method of clustering is a good fit between acoustic signals and damage mechanisms and time of events. Cumulative events of Acoustic emission Amplitude obtained from damage mechanisms of both composite are in the same range and Acoustic emission duration of carbon-epoxy is more than carbon-epoxy nanomodified composite.