The electrical properties and phase transition behavior of (Pb0.87La0.02Ba0.1)(Zr0.6Sn0.4KxTix)O3 solid solutions (PLBZST, 0.04%x0.2) were investigated by the X-ray diffraction, permittivity, pyroelectric current, and P-E electric hysterisis loops. As the composition x increased from 0.04 to 0.2, the antiferroelectric ceramics (x%0.07, AFE) with tetragonal phase changed to the ferroelectric relaxors (RFE, 0.09%x). AFE ceramics showed a peculiar diffuse phase transition and dielectric relaxation at the low temperature (down to K100 8C) due to a frustration between AFE and FE state. With an increase in composition x, electrically field-induced AFE-FE switching field (EAFE-FE) and AFE-paraelectric (PE) phase transition temperature (Tc) are depressed in the temperature (T)-Ti composition (x) phase diagram, a FE-AFE-PE triple phase point (Ttr) with the lowest transition temperature occurred at xZ0.09. The pyroelectric currents under an application of various external electric field (E) were measured to identify a T-E phase diagram of the PLBZST compound.