In order to improve the oxidation resistance and mechanical properties of flexible graphite materials,by using magnesium borate,phosphoric acid,sodium silicate and ethylene glycol as impregnants,the flexible graphite materials were modified by liquid-phase impregnation method,and the optimum impregnant ratio and impregnation process were determined by single factor experiment.The results show that the tensile strength,compression rate and leakage rate of the high temperature resistant flexible graphite materials prepared by the optimum conditions are significantly improved,the tolerance temperature of the prepared flexible graphite material is increased from 450 ℃ to 800 ℃.The percentage of thermal weight loss after calcination at 800 ℃ in an aerobic environment for 1 h is decreased to 6.98%,indicating that liquid impregnation can effectively improve the hightemperature resistance of flexible graphite materials and enhance the mechanical properties of the materials.SEM analysis results show that magnesium borate,phosphoric acid and sodium silicate form a glasslike protective layer inside and on the surface of flexible graphite at high temperature,and fill the micro pores inside to block the contact between oxygen and graphite,which isolate the contact between oxygen and graphite,and delay the oxidation reaction between flexible graphite and oxygen.