This study deals with the impact of a thermal conditioning (thermal aging and thermal cycling) on a carbon fibers cross ply laminates. Special attention has been paid on the cracks initiation and propagation depending on the parameters of the thermal conditioning (temperatures, time, and number of cycles). The first part presents the manufacturing method and some preliminary studies. Then the report is focused on the thermal conditioning (experimental method and results). In the last part, some theoretical studies about the thermal stresses and a simulation of the crack density evolution are presented.