The invention discloses a cement concrete pavement cavity drop hammer type Benkelman beams deflectometer comprehensive detection method. The method comprises the following steps that S1, preparation work is done, in specific, a Benkelman beams deflectometer is conditioned, detected, aligned and turned on; S2, testing is conducted, a bearing board falls down, a drop hammer device is started, a sensor and the bearing board are lifted up, calculation is conducted, heavy hammers with different levels of mass of the drop hammer type Benkelman beams deflectometer fall the certain height to generateimpact load, instant deformation occurs on the pavement surface, and the dynamic deflection and deflection basin generated under the dynamic load effect are tested. The dynamic modulus of elasticity of each layer of the pavement is calculated inversely, and serves as the void determination parameters of the cement concrete pavement, when any one of the intercept, the single-point deflection and the deflection different does not meet the requirement, it is deemed that voids exist beneath a board block, and the device is convenient to operate and suitable for being widely popularized.