The cold-atom gravity gradiometer utilizes the quantum state superposition characteristics of atoms and the interferencecharacteristicsof matterwavestomeasureabsolutegravitygradientinformationwithhighaccuracy, lowdrift, andselfcalibration.Ithasimportantapplicationprospectsinthefieldssuchasdeepground/deep-sea resourcedevelopment, geological disaster warning and prevention, battlefield environment construction and combat support, and earth science research. Inthispaper, thebasicprincipleandthedevelopment statusofcold-atomgravitygradiometer areintroduced.The pain points and difficult problems of cold atom gravity gradiometer are analyzed. Finally, partial solutions to the difficult problemsandthedevelopmenttrendofcold-atomgravitygradienterarediscussed.