Abstarct: Determination of the transition limit from open-pit to underground mining, particularly under operational constraints arising from the presence of the Line 4 plant facilities at Goharavsh Pelikam and their influence on the advancement of open-pit mining in Gol-e-Gohar Mine No. 2, constitutes one of the principal issues in mine design and planning and is regarded as a significant factor in profitability and the optimal exploitation of mineral reserves. The present study was conducted with the objective of determining the transition depth baxsed on economic modeling, whereby the net values of mineral blocks under open-pit and underground mining scenarios were compared. In this context, the block value subtraction method, together with extraction prioritization, was employed to identify the blocks with higher economic value in each section. The results indicate that, assuming an open-pit mining limit at the 1490 m elevation and maintaining a minimum distance of 13 m and a maximum distance of 121 m from the plant facilities, expansion of the ultimate pit is feasible at a distance of 73 m from the plant. In addition, baxsed on a comparative assessment of the modified Nicholas method and the UBC criteria, the Sublevel Caving method was selected as the most appropriate underground mining alternative. Ultimately, a practical decision-making model for determining the transition boundary is presented, which can provide a scientific basis for long-term mine planning in this mine.