When a compression is applied to a fully poled ferroelectric polycrystal at an angle θ to the original poling direction, its nonlinear electromechanical response is dependent on such an angle. Here we report our investigation on such an orientation dependence on the electromechanical behavior of lead zirconium titanate (PZT) under compression. The measured stress-electric displacement and stress-strain curves exhibit strong angle dependence and nonlinear behavior under compression. The experimental results indicate that as the loading direction changes from 0°, to 30°, 45°, 60°, and finally 90° to the initial poling direction, the magnitude of the electric displacement and mechanical strain all decrease. Then a micromechanics theory based on irreversible thermodynamics and physics of domain switch was applied to study this orientation effect on the electromechanical coupling behavior under compression. The comparisons between our experimental data and theoretical prediction are found to be in reasonable agreement.