The influence of B-site deficiency on the stability of electrically induced long-range ferroelectric order of the stoichiometric Bi0.5+xNa0.5-xTi1-0.5x0.5xO3 (BNT-xV(Ti)) ( denotes vacancies) ceramics is studied. The depolarization and ferroelectric to relaxor transition are identified as separate and discrete processes in BNT-based materials. For BNT-0.02V(Ti), the resonance and anti-resonance peaks on dielectric permittivity-frequency curves indicate dominating ferroelectric phase at room temperature. The depolarization temperature, determined by thermally stimulated depolarization current, is 65 degrees C. However, the ferroelectric to relaxor transition temperature is absent, as no distinct frequency-independent anomalies for the dielectric permittivity exist. This depolarization process can be ascribed to nanoscale ferroelectric domain at room temperature for BNT-0.02V(Ti), which is induced by chemical disorder and strong random field as V-Ti generated. Hence, the results imply that the B-site deficiency in BNT is a very effective route to tailor the stability of electrically induced long-range ferroelectric order.