The invention discloses a device for eliminating electro-optical crystal depolarization. The device comprises an electro-optical crystal, a first 90-degree optical rotator, a second electro-optical crystal and a second 90-degree optical rotator, and lasers are injected from a first electro-optical crystal switch, sequentially pass the first 90-degree optical rotator and the second electro-optical crystal and are outputted from the second 90-degree optical rotator. The device can eliminate angle depolarization of the electro-optical crystal caused by angle inclination of the injection lasers, output energy and beam quality of lasers are improved, and the device has important application to laser amplifiers.