TiO2 sculptured thin films are prepared by oblique angle electron beam deposition. After heat treatment at different annealing temperature and time, the properties of birefringence and phase retardance are optimized. The results illustrate that the optimum annealing condition is for 4 h at 500 ℃ and the maximum birefringence is up to 0.115, which is far higher than the as-deposited films. According to the measurement of ellipsmetry, the phase retardance is about 90°at 550 nm, which means that it is suitable as a wave plate. Therefore, thermal annealing is a useful and feasible method to improve birefringence of sculptured thin films.