bThe types, formation mechanism and suppressing approaches of structural defects in PMNT crystals grown by a Bridgman method were investigated in this paper. The structural defects include composition non-uniformity, scattering particles, pores, negative crystal structures, cellular structures, fissure structures and point defects. They are formed due to one or several of the following: composition deviation, incomplete melting and diffusion, high-temperature volatilization, temperature fluctuation and instability of the position and shape of growth interfaces. On understanding the formation mechanism of structural defects, one can restrain them by means of adjusting stoichiometry of starting materials, using PMNT crystal bulks, suppressing composition volatilization and modifying growth parameters.