The simulation of complex production systems is widely used for the evaluation of any change of the production system and the prediction of their behaviour. However, simulation models are subjects to several errors. The validation of models through a real case study is a very effective way to get reliable models. This contribution aims to present the processing of validation of a model of a real production system. The evaluation model that we propose is based on Hierarchical Coloured PetriNets and simulation (HCPN). HCPN allow the analysis and description of the production system. The simulation allows to make predictions about performance during the production (simulation period). We illustrate our methodology through a real case, which is that of an assembly line with non-deterministic process times.This paper presents the study of the real production line, the presentation of the model based on HCPN, and simulation results of the validated model using the simulation platform Petri Nets CPN TOOLS. It tray to explain the causes the diference between the real and simulated models.