The crystal monochromator is an important device in the synchrotron radiation beam line. It uses the Bragg diffraction principle of the crystal to monochromatize the continuous spectrum of synchrotron radiation. The twin-crystal monochromator is one of the important ones, and it consists of two crystals placed in parallel. Among them, the front-end crystal uses a liquid nitrogen cooling device to resist high heat load; the back-end crystal uses a high-precision and high-resolution adjustment mechanism to ensure that the exit beam direction of the dual-crystal monochromator remains unchanged.