Abstarct: Due to the increase in demand and the need to increase production and also the emergence of many problems due to surface mining of building stone mines such as noise pollution, environmental degradation, etc. should be towards the use of underground mining methods. The deposit in question in this research is Kapiol travertine mine in Sarcheshmeh Mahallat mining complex with a reserve of 1.326 million tons, which has an overburden of about 60 meters and an average thickness of 6 meters. In this research, in order to design this mine, numerical methods and FLAC3D software have been used. To do this, first the information required for mine design is collected and then, using experimental formulas, the baxse numbers to start modeling are obtained .Numerical modeling has been started using these numbers and by examining the results of the implementation of these models, an attempt has been made to achieve the best recovery and safety .In order to achieve the highest possible recovery in different models, an attempt has been made to reduce the dimensions of the stone columns of the mine and increase the dimensions of the rooms .To achieve the required safety in each model, the maximum displacement values are compared with the allowable displacement value of that model .Finally, the model with a baxse width of 4 meters and a room width of 11 meters has been determined as the final model with a recovery of 92.89%, a ceiling safety factor of 1.66 and a pillar safety factor of 2 .Finally, preparation design, equipment and machinery, technical services, ventilation system and operation plan have been done.