In order to accurately capture the impact factors of the equipment reliability parameters, such as geographical region, outage liability reasons, and available repair resources, an accurate model of reliability parameters is proposed for equipment of distribution network in this paper. Firstly, with the historical data categorized according to the outage liability reasons and the proposed refined modeling standards, an accurate failure rate model of equipment is established. Then, according to the actual workflow of fault repair adopted by the grid operator, an accurate repair time model of distribution network equipment is established. Finally, the reliability assessment of medium-voltage distribution network is performed with the reliability parameter model and the the block algorithm. Case studies on an actual distribution network show that compared with the traditional parameter model, the proposed parameter model can obtain specific reliability parameters according to the characteristics of the equipment. The results of reliability evaluation of distribution network are more consistent with the statistical level of system reliability, and have higher reference value for the identification of critical components.