Locating piezoelectric patches on structures under compressive forces as a sensor or actuator can predict or increase the buckling load of the structure. In this article, using particle swarm optimization algorithm, the location and pattern of piezoelectric patches on a plate to achieve maximum buckling load are investigated. For boundary condition of the plate, four different conditions are considered. The piezoelectric patches have more effect on critical buckling load for Clamp-Free condition and less effect for Clamp-Clamp condition. The voltage of patches has a linear effect on increasing the maximum critical buckling load. The results show that locating piezoelectric patches near the clamp edge has more influence on critical load than locating the patches near the simply support or free edge. The results in this article are validated by comparing to the results reported in the previous publication.