The microstructure of oriented Pb(Zr0.7Ti0.3)O-3 thin films prepared via the sol-gel method has been carefully investigated. After the precursor was heated, the resultant thin film displayed (100)-preferred orientation because of accumulation of the colloidal particles. X-Ray diffraction (XRD) result indicated that the strong [100]- or [111]-preferred orientation of the PZT thin films could be observed when the substrates slightly bend under appropriate external stresses during annealing procedure. Atomic force microscope (AFM) images revealed that (100)-oriented grains aggregated in some separate zones. The above results can be well explained in the view of internal stress during crystallization.