Abstract: Little g, a position dependent and time varying quantity, has very important applications in resource exploration, geodesy, metrology, and other fields. A gravimeter is an instrument used to obtain gravity data, which may be relative or absolute according to how the scale factors are obtained. An absolute gravimeter can directly compare and apply measurements across time and space, so it is of more interest. Since there is no mechanical wear, an atomic gravimeter can provide precise and accurate measurements of gravity for long continuous periods of time. In this paper, the basic principle, physical realization, and figure of merit parameters of atomic gravimeters are reviewed, followed by a brief introduction to their current and future development at home and abroad.