Abstract: Based on pavement damage, one of the transverse crack as an example, put forward a kind of image analysis based on the FPGA realization method of pavement damage detection device.The device adopts the Sobel algorithm, and through the Verilog HDL language programming implementation on FPGA development board to enter the road image analysis and feature extraction.The result of the judge is dealing with the analysis of crack damage.In order to improve the detection accuracy and anti-interference ability, the method of Sobel algorithm with variable denominator difference operation, and the morphology after image binarization processing corrosion expansion.Through the simulation and experiment show that the detection device can accurately detect cracks.