This article examined the issue of selection heuristics for the ABB algorithm, a branch-and-bound method for determining the optimal solution structure in P-graphs. Previous studies have not investigated the possible effects of different heuristics on the running time of the ABB algorithm. In this study, we represent the results of applying three basic heuristics in randomly generated P-graphs. In particular, for P-graphs with matrix patterns, the LIFO heuristic is recommended because it performed the best, while the FIFO heuristic had the slowest running time.