In this paper, a structure of relaxation ferroelectric single crystal three-axis acceleration sensor suitable for low frequency measurement is proposed. Each coordinate axis of the acceleration sensor is composed of a single crystal bending beam sensitive element. Through the finite element simulation, the influences of the structure dimension parameters of the thickness of the single crystal layer, the thickness of the metal layer of the base beam, the material of the base beam etc. in the bending beam structure on the resonance frequency and acceleration sensitivity are analyzed, and the optimal structure size is obtained, and a relaxation ferroelectric single crystal three-axis acceleration sensor prototype is developed and tested. The test results show that the single crystal three-axis acceleration sensor has good consistency in all directions, and the sensitivity of the acceleration sensor is up to 86.1 mV/(m·s-2),and can work in the low frequency band of 10~400 Hz.