<p>Porous piezoelectric nanobeams, as the basic structural components of piezoelectric sensors, can be used for blood pressure monitoring in medical fields and for energy harvesting and self powering in wireless sensors, and their mechanical properties are often affected by surface effects. In this work, we focus on analyzing the characteristics of the buckling and post-buckling behavior of graded porous piezoelectric nanobeams with surface effects. In doing this, we first introduced the renowned Gurtin–Murdoch surface elasticity theory and combined it with geometric nonlinear theory for extensible beams to establish control differential equations for post-buckling, where surface effects, piezoelectric effects and pore influence are considered simultaneously. In this way, the total structure can be seen as a three-layer structure consisting of a main layer and two surface layers, where the pores of the graded porous piezoelectric nanomaterial serving as the bulk layer is unevenly distributed in two cosine forms along the thickness direction. Then, shooting numerical method is employed to solve the governing equations containing multiple variables of problem for external pressure and voltage. The proposed mechanical model was validated by comparing the obtained results with those in the literature. Finally, a detailed analysis was conducted on the surface and piezoelectric effects of porous piezoelectric nanobeams under different pore and pore distribution patterns. These new findings can provide technical guidance for the precise design and manufacturing of porous piezoelectric nanosensors in the medical field.</p>