Modern piezoelectric transducers normally have complicated structures and work under severe loading conditions. Due to their inherent domain-switching processes, the real response of piezoceramics under large-signal loading is dominated by a significantly non-linear behavior that is to be considered in reliability assessment and devices design. This paper presents systematic measurements of the non-linear depolarization and strain behavior of soft lead zirconate titanate piezoceramics over a wide range of compression loads and bias electric fields. An attempt has been made to explain the experimental findings by simultaneously taking into account the contributions of dielectric response, elastic deformation, irreversible domain switching, and piezoeffects.