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Reliability analysis for Electronic and control system and providing a model to express the relationship between the various components have crucial importance. This study proposes a methodic approach to analyze the electronic and control system of mechanical system reliability in early design phase with deficiency of the sufficient field data available. In this method, first the different components of the system are identified. The function configuration and relate to each other are considered. Using generic data available through various different standards such as MIL-HDBK-217F and EPRD, failure rate and mean time between failures (MTBF) are calculated for each component. Applying this information, the system reliability model is developed and the relations between components in terms of reliability are explained. In this context, the computation is completed to analyze the reliability of the system. The importance measure technique is utilized to determine the importance of various components of the system. Also using reliability allocation method, reliability of each component is calculated to evaluate the modification required to upgrade the system to the specified reliability goal. Finally, considering the maintenance data of each component, availability estimations and related properties are obtained. As an application, this method is applied on the electrical and control system of a horizontal drilling machine. The results are discussed with concluding remarks in suitability of the proposed methodology.