This article assesses the reliability and readiness level of the open-pit drilling rigs used by the ”Erdenet Mining Corporation” in Mongolia. The assessment is based on a dynamic system model that predicts the reliable operation of the drilling rigs from 2010 to 2030. The model incorporates quantitative data on rig breakdowns and repairs from 2006 to 2019, using mathematical formulas based on Markov chain and Weibull distribution laws. The model’s unique feature lies in its use of ordinary differential equations, random process theory, distribution laws, and system dynamic modeling methods, allowing for easy performance of experiments and simulations. The certainty of drill-rig breakdowns necessitates minimizing damage and ensuring continuous and reliable mine operation. To enhance the drilling rig’s reliability, two methods are proposed: improving maintenance or purchasing new equipment. The article aims to calculate how these methods will impact the reliable operation of the drilling rig and determine the most economically beneficial option.