The industrial maintenance takes an increasing importance and appears to be one of the key functions of the modern production company.Our work is devoted to the theoretical and practical study of the reliability of the rolling stock at the level of the company "E.T.U.S.T", in this case the industrial maintenance based on advanced methods and modern tools of the reliability.In our project we have used the reliability laws and the analysis methods, types (PARETO and ABC) which are known in the field of preventive maintenance, and in particular the law of "Weibull", in order to concretize in reality our study. We have defined the graphical and analytical methods to determine the reliability parameters, which are used for the evaluation of the degradation rate of the equipment of the park and determine the type of maintenance to be applied.Finally, we validated the results found by a practical case study, by selecting the sensitive organs of strategic equipment in the company. This study allowed us to find positive results in conformity with the practical reality at the company level by using an advanced calculation code.