We have prepared antiferroelectric ceramics with compositions of (Pb0.97La0.02)(Zr1-x-ySnyTix)O3(x=0.09 or 0.1; 0.16≤y≤0.38) near antiferroelectric (AFE)tetragonal-ferroelectric (FE)rhombohedral morphotropic phase boundary. The effects of Sn content on electric field-induced AFE→FE switching field Ec, double-hysteresis-loop width ΔE, and temperature-induced FE→AFE phase transition temperature TFE, AFE→paraelectric (PE) transition temperature Tc are investigated. At constant Ti content x, both TEF and Tc decrease with increase of Sn content y. Electric hysteresis loop measurement demonstrates an increase of Ec and decrease of ΔE when Sn content y　increases. Furthermore, we also find that Ec and ΔE are related with TFE and Tc. In situ X-ray diffraction under dc bias field shows that symmetry changes from tetragonal phase to rhombohedral phase with an increase of c axis,and an increase of lattice volume.