Abstract: The excellent thermal conductivity close to natural diamond sends Chemical Vapor Deposition（CVD）diamond film the most perfect material for heat spreader.Diamond film heat spreader was deposited by Microwave Plasma CVD（MPCVD） method,and the influences of different deposition conditions on the thermal conductivity of diamond heat spreaders were studied.Surface morphology and purity of the deposited diamond films were detected by SEM and Raman spectrum.The thermal conductivity of diamond heat spreaders were characterized by testing the temperature change of the LED cells encapsulated on it.The results showed that in other conditions remain unchanged,higher output of the microwave source,lower working pressure and higher substrate temperature were propitious to the growth of diamond films with better thermal conductivity.