The dielectric properties of (Pb0.85Ba0.11La0.03)(Zr0.76Sn0.20Ti0.04) (PLZSTB11) composite ceramics have been investigated systematically. The characteristic of PLZSTB11 was that it demonstrated antiferroelectricity. The dielectric constant increased, then decreased sharply with increasing DC electric field, and a low loss also was obtained under DC electric fields (=40kV/cm). The low loss (tand 0.003) and the highest tunability (65%) were obtained for the PLZSTB11 ceramics around 50 degrees C, indicating that it is a promising candidate for bi-tunable materials nearby room temperature. The dielectric properties of PLZSTB11 composites under a DC bias field can be useful for the design of devices and practical applications.