Thermal processes of carbon fiber‐reinforced composite parts curing cycle were studied experimentally and by mathematical simulation. Flat panel, T‐stringer, and five‐stringer detail based on tetrafunctional MY721 epoxy resin were investigated. Application of standard curing cycle (heating followed by isothermal exposure at 180°C) leads to the overheating of 28°C in flat panel and of 30°C in T‐stringer of 24 mm thickness. The model considers the vacuum bag with auxiliary materials as separate layers. This approach allows to simulate the shifting of thermal field to the vacuum bag side. Simulation results show good agreement with the experimentally observed temperature fields. The model helps to optimize the curing cycle to reduce the local overheating. The same temperature regime could be used for all three geometries. Therefore, the optimization can be carried out only for the simple‐shape parts to save the calculation time and simplify experiments at the stage of model testing. POLYM. COMPOS., 37:2252–2259, 2016. © 2015 Society of Plastics Engineers