In the fields of structural health monitoring, seismic monitoring, and aerospace, low-frequency micro-vibrations with frequencies below 10 Hz and amplitude less than 1 mm need to be measured accurately. The acceleration values of low-frequency micro-vibrations are on the order of mg ~ μg, while the sensitivity of existing commercial accelerometers is mostly below 0.5 V/g, which can no longer meet the requirements. In this paper, high-sensitivity low-frequency optical accelerometers is carried out. Based on the sensing principle of accelerometers, the technical requirements related to the design of low-frequency accelerometers are determined through theoretical modeling, and one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) elastic mechanisms are constructed by using leaf springs and flexible hinges as elastic elements with single and multiple seismic masses; based on high-precision optical sensing principles such as the principle of image dispersion, laser triangulation, and laser auto-collimation, a high-sensitivity optical sensing system is designed. 1D, 2D and 3D low-frequency optical accelerometers have been designed and their performance has been verified by experiments, with sensitivity better than 9 V/g and resolution better than 1 mg, which can be used for low-frequency micro-vibration measurements.