Li(1-2x)CoxMnPO4/C　composite　cathode　materials　for　lithium　ion　battery　are　synthesized　by　sol-gel　method　with　following　heat-treatment　in　the　air.　Environment　scanning　electron　microscopy　measurements　show　that　the　particles　are　irregular　and　inhomogeneous,　and　that　particle　sizes　slightly　enlarge　with　the　elevation　of　sintering　temperatures.　Powder　X-ray　diffraction　analysis　indicates　that　the　samples　are　olivine-structured.　Electrochemical　tests　indicate　that　the　optimal　sintering　temperature　registers　400　degrees　C,　and　that　the　cyclic　ability　of　LiMnPO4　is　greatly　improved　by　doping　Co2+.　When　tested　at　0.02　C　rate　between　2.8　and　4.4　V,　the　initial　discharge　capacity　of　the　sample　with　initial　composition　of　x=0.07　sintered　at　400　degrees　C　reaches　112.2　mAh/g,　after　70　cycles,　the　capacities　remain　58.8mAh/g.