Attributable to high competition in global manufacturing market and outsourcing suppliers, many supply chain systems have become more complex and faced with high risks and low performance. Many financial losses and failures are likely to be due to risks among supply chain's components. As a prescription to improve quality, performance, and profitability of the supply chain, companies would like to measure and optimize the reliability of the entire supply chain system. Also, companies are interested in minimizing the cost of processes and improvement throughout the supply chain system. This paper explains a statistical method that measures the reliability rate of each part in the system as well as the entire supply chain. Moreover, the paper elucidates a mathematical model that improves the reliability of the supply chain through minimization of cost components. The results and findings of this study confirm that the proposed model can be applied to improve the supply chain system. Also, the system can be improved to reach a designed reliability rate as given target to the model. The illustrated methodology can be used as a guide on how to develop a reliable supply chain system plan with low possible costs.