CaMg(CO3)2　microspheres　were　prepared　and　used　as　hard　templates　to　fabricate　a　series　of　CaMg(CO3)2@Ag2CO3　composite　microspheres　via　a　fast　and　low-cost　ion　exchange　process.　The　effects　of　ion　exchange　time　and　temperature　on　the　physicochemical　properties　and　photocatalytic　activities　of　the　composite　microspheres　were　studied　through　photocatalytic　degradation　of　Acid　Orange　II　under　xenon　lamp　irradiation.　The　obtained　samples　were　analyzed　by　X-ray　diffraction,　scanning　electron　microscopy,　Fourier　transform　infrared　spectroscopy,　UV-vis　diffuse　reflectance　spectroscopy,　N2　physical　adsorption,　and　photocurrent　tests.　The　CaMg(CO3)2@Ag2CO3　sample　with　the　highest　activity　was　obtained　with　an　ion　exchange　time　of　4　h　and　temperature　of　40　°C.　The　degradation　rate　of　Acid　Orange　II　by　this　sample　reached　83.3%　after　15　min　of　light　irradiation,　and　the　sample　also　performed　well　in　phenol　degradation.　The　CaMg(CO3)2@Ag2CO3　produced　under　these　ion　exchange　conditions　showed　a　well-ordered　hierarchical　morphology　with　small　particle　sizes,　which　was　beneficial　to　light　absorption　and　the　transfer　of　photoelectrons　(e−)　and　holes　(h+)　to　the　catalyst　surface.　Moreover,　the　separation　of　photogenerated·carriers　over　the　composites　was　greatly　improved　relative　to　bare　CaMg(CO3)2.　Despite　the　very　low　content　of　Ag2CO3　(2.56%),　excellent　photocatalytic　performance　was　obtained　over　the　CaMg(CO3)2@Ag2CO3　microspheres.　©　2017　Dalian　Institute　of　Chemical　Physics,　the　Chinese　Academy　of　Sciences