Abstract: In-situ polymerization was adopted to prepare a structure-stable and leakproof phase change microcapsule,which was composed of paraffin as heat storage core material,titanium dioxide and chitosan as shell and graphene nanoplatelets（GNP）as thermal conductive filler. SEM、FTIR、TGA、DSC and thermal conductivity tester were used to investigate the effect of different core-shell ratio and GNP filling amount on the microstructure,surface functional groups,thermal stability,phase transformation and thermal conductivity of microcapsules. The results indicated that microcapsules have a compact structure and good leakage resistance. The maximum phase change latent heat of the microcapsules is 134.78 J/g,and the corresponding coating rate is 75.51%. The thermal conductivity of microcapsules increased by 261.5% due to the introduce of GNP.