Frequency (f) dependence of coercive field (Ec) of six Pb(Zr-1-Ti-x(x))O-3 (0.20 <= x <= 0.60) bulk ceramics with different compositions was investigated at various frequencies (1-100 similar to Hz). Scaling relations of E-c against f, E-c alpha f(beta), were obtained, where the value of exponent beta varied with the ceramics composition. These exponents were far smaller than that of the theoretic prediction because the domain wall motion played a major role in the frequency region. In addition, the values of the exponents were of obvious discrepancy for different phase structures with tetragonal, rhombohedral, and morphotropic phases, but nearly similar for the same phase structure with different compositions, suggesting that different domain structures influence the scaling behaviors.