The nonlinear governing equations on the electromechanical coupling and carrier concentrations are established for a static piezoelectric PN junction subjected to a pair of tensile/compressive stresses at the endpoints. Numerical results show adjustability and controllability on the fundamental characteristics of a piezoelectric PN junction by mechanical-loading. A pair of tensile-stresses induces enlargement of both depletion layer width and contact potential difference of a piezoelectric PN junction, where the majority carrier concentration is increased and the minority one is decreased. Thus, potential barrier of the PN junction is raised by tensile-stressed loading such that it becomes more difficult to break-through. Correspondingly, a pair of compressive-stresses results in diminishing of depletion layer width and contact potential difference of a piezoelectric PN junction, where the majority carrier concentration is decreased and the minority one is increased. Thus, potential barrier of the PN junction is reduced by compressive-stressed loading such that it becomes easier to break-through. Moreover, analysis indicates that a shorter distance between the loading point and the depletion layer is able to produce better adjustment and control effect. This technique by coupled electromechanical fields and carrier concentrations as a whole has some referential significance to piezotronics.