With global industrialization and population increase, the constraints of fossil fuels in terms of price and environmental protection necessitate the development of alternate energy sources. Ethanol reforming, as a non-fossil-originated hydrogen production process, has become an industrially promising reaction. In this work, perovskite titanate (La0.5Ca0.5)(1-α)Ni0.06Ti0.94O3-δ with different A-site deficiency was synthesized via a modified Pechini method. Orthorhombic titanates with grain size of 200 to 500 nm were obtained with nickel cooperated into the frameworks. The extent of A-site deficiency influences the size and population of exsolved nickel particles. Higher A-site defects would greatly induce the exsolution of nickel, thus promoting the catalytic activity in ethanol steam reforming reaction. La0.4Ca0.4Ni0.06Ti0.94O3-δ sample showed an outlet composition that was closed to thermodynamic equilibrium under S/C = 3 and WHSV = 8.8 gethanol/(gcat·h). The metal agglomeration was inhibited during 8-hour reforming at high temperatures, while the deactivation during the stability test was mainly due to the formation of graphite carbon.