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.