As single crystal of lead zirconium titanate (PZT) is difficult to produce, all of its ferroelectric properties are not clarified perfectly. In this paper, the ferroelectric properties of PZT single crystal have been identified computationally from ones of PZT ceramic by steepest decent method and multiscale finite element modeling based on a crystallographic homogenization method. Crystallographic homogenization method enables us to predict macroscopic properties of ceramics considering microscopic in-homogeneous structure in an aggregation of crystal grains. Crystal morphology of PZT ceramic has been measured by SEM·EBSD technique, and it has been introduced to microscopic finite element model. Then, the ferroelectric properties of crystal grain were surveyed by steepest decent method to correspond its macroscopic ones to experimental values of PZT ceramic. The proposed computational procedure has been applied to barium titanate, and its validity has been proved by comparison of identified ferroelectric properties with already-known ones of single crystal. Finally, the identified ferroelectric properties such as elastic compliance, dielectric and piezoelectric constants were presented for PZT single crystal.