Temperature dependent piezoelectric properties of ferroelectric relaxer single crystals, particularly the cerium-doped strontium barium niobate compositions (SBN60 : Ce), were investigated by resonance and anti-resonance technique. Characteristic resonant frequencies (f(r)-f(a), f(s)-f(p), and f(m)-f(n)) were studied using equivalent circuit simulation. Piezoelectric resonance in a relaxer resonator persists into temperatures much higher than T-m (the temperature at which dielectric constant, kappa, has a maximum at 1 kHz) in comparison with the normal ferroelectrics such as TGS. The parameters in an equivalent circuit, however, are phenomenally different from a normal resonator like a TGS, near and above the transition temperature region. The significance and understanding of the piezoelectric resonance characteristics in ferroelectric relaxer are discussed.