As pavement crack images are difficult to segment due to the existence of high noise,weak boundary andsmall cracks,an extraction method of pavement cracks based on the valley edge detection of fractional integral isproposed.In this method,first,neighboring smoothing of the original image is performed to eliminate the noise andexpand the relative width of the cracks.Then,the main cracks are extracted via the valley edge detection of frac-tional integral,and the resulting image is further processed via the morphological approach with short- line noiseelimination. Afterwards,final cracks are extracted by using the gap linking method on maximum entropy thresholdto cause cracks to merge automatically. Experimental results show that the proposed method instantly helps to detectsmall pavement cracks with high accuracy and strong noise robustness.