Determining the limit of underground mining and stope layout is one of the most important points in underground mining and production planning. Numerous algorithms have been offered to address the stope layout optimization problem both in two-dimensional and three-dimensional space based on economic value. In this paper, a new heuristic algorithm with different strategies was developed to generate optimal and sub-optimal underground stope layouts. In this algorithm, all possible stopes were created based on an entirely economic block model considering stope dimensions in the three-dimensional space. Afterward, the algorithm generated a family of non-overlapping stopes over all possible stopes and selected the highest economic value as the final solution.  Also, a user-friendly computer program named Stope Layout Optimizer (SLO3D) was designed in C# object-oriented program, and two separate examples were set for a better understanding of the algorithm. The application of the proposed computer program was implemented on a real copper deposit, considering three different strategies. The final output consisted of 29 stopes with a value of US$ 37 million. The results proved that the new heuristic algorithm was able to increase the final economic value by 49.04% compared to the floating stope method. Furthermore, the three proposed strategies were investigated for the same deposit. The results of this procedure illustrated that the probabilistic approach could generate higher economic values and sub-optimal values compared with the other two strategies discussed in previous studies regarding this issue.