Two types of ferroelectric random memory are irradiated and annealed by 60Co γ-rays. Total Ionizing Dose(TID) failure mechanism of the device is analyzed at different biases. DC,AC and function parameters of the memory are tested through irradiating and annealing by Very Large Scale Integrated circuit(VLSI) test system. The radiation-sensitive parameters are obtained through analyzing the test data. The results show that the functional failure thresholds of ferroelectric memory are different at different biases, because different biases lead to different fragile circuit modules due to irradiation damage.