Abstract: Basic principles of highway pavement thickness Ground Penetrating Radar(GPR) detecting were briefly introduced. Nondestructive test of Lianhuo section of highway through the Sanmenxia City was carried out by use of TerraSIRch SIR-3000 GPR system produced by GSSI Company of the United States. Finally the layers average thickness and standard deviation in highway pavement were calculated. Meanwhile the interactive interpretation of GPR can get the continuous and clear thickness curve, which will be conducive to the further detailed explanation of GPR thickness detection.