Nano-crystalline Pb0·72La0·28TiO3(PLT28) thin films were prepared on glass substrate by RF magnetron sputtering using the sequence of post-deposition annealing process. 150 to 200nm thick films were found to be comprised of 5nm grains in the perovskite structure. The effective birefringence shift in the nano-PLT films as a function of applied electric field exhibits a quadratic electro-optical behavior. The hysteresis measurement indicated that the films display slim-loop character. Experimental results showed that the nano PLT film is an electric fieldinduced ferroelectric.