Samples of 0.9Pb(Fe1/2Nb1/2)O3-0.1PbTiO3 were mixed with ZnO at 0, 1, 2, and 3 wt.%, and were synthesised by mixed oxide through a two-step sintering method. Phase transition of the samples was analysed by using X-ray diffractometer (XRD) and Fourier transform infrared spectroscopy (FTIR). The dielectric properties were determined by LCR meter at 1 kHz, 10 kHz, and 100 kHz. The results showed that the morphotropic phase boundary of 0.9PFN-0.1PT shifting to tetragonal phase and suppressed pyrochlore phase when ZnO was added into 0.9PFN-0.1PT. In addition, FTIR spectra peak showed zinc and oxygen bond bonding vibration at frequencies range 3,452 cm-1 and 3,792 cm-1 after level doping ZnO of 3 wt.%. The samples exhibited the maximum dielectric constant at temperature for 144°C. The dispersion of dielectric constantly decreased with increasing ZnO contents. The relaxor ferroelectric of 0.9PFN-0.1PT ceramic shifted to normal ferroelectric with increasing ZnO contents.