Abstarct: Maintaining the reliability of the electricity network at the optimal level and improving its sustainability seems necessary due to the growing network development and the use of electrical energy in various industries. The protection system has a significant role in maintaining quality and improving the reliability of the electricity industry. The protection system consists of different equipment such as protective relays, measuring transformers, and pressure keys. The capacitive voltage transformer is one of the important measurement equipment, which is widely used in the power grid at moderate and high pressure levels to prepare the voltage signal for control and protective equipment. The measuring accuracy of this equipment plays a significant role in the proper operation of the protection system and ultimately, the sustainability and reliability of the power system. Therefore, maintaining the accuracy of the capacitive voltage transformer during its lifetime is of great importance. To achieve this goal, maintenance activities should be made suitable for equipment conditions. This requires the evaluation of the reliability of the capacitive voltage transformer during its lifetime. So far, a good model has not been provided to assess the reliability of this equipment. Therefore, in this research, a Markov model is proposed to evaluate the reliability of the capacitive voltage transformer. To extract the proposed Markov model, initially, the capacitive voltage transformer is divided into three Capacitor voltage dividers (CVD), Electromagnetic unit (EMU) and Bushing, and a Markov model is provided for each subsystem. Then, the extensive 10-state Markov model for CVT is obtaining by combining the proposed Markov model of each subsystem. According to the numerical analysis and simulation results, it is observed that the capacitive voltage transformer operates in a healthy state and with appropriate measurement accuracy for most of its operating life. Sensitivity analysis is performed to evaluate the effect of failure and repairing rates different elements of capacitive voltage transformers in the availability of this equipment. The simulation results show the effectiveness of the Markov model in assessing the reliability of the capacitive voltage transformer