A novel resonator for compensating thermal induced birefringence and self-selecting mode is designed. Based on the depolarization characteristics analysis of Nd:YAG rod, the properties of compensating depolarization loss and self-selecting mode, and the stability of resonator are discussed. The technology uses a feedback mirror to compensate depolarization, which makes the resonator contain three sub-resonators with different abilities of mode selection. The resonator is applied to a diode-pumped Nd:YAG laser operating at acoustic optical (AO)-Q switch for acquiring high quality beam.