The shape is one of the most important features in pomelo quality test and classification.Aiming at pomelo′s shape inspection,an inspection algorithm for pomelo′s shape based on contour directional feature is presented using image processing.The texture gradient operator is firstly introduced,directional entropy function is defined to obtain the directional angle of pomelo′s profile points,which is used to extract and encode pomelo′s contour.And then contour directional histogram is established to describe the distribution on shape′s directionality as pomelo′s shape feature.During inspecting process,pomelo shape′s inspection can be realized by means of calculating correlation coefficient between contour directional histograms.The experiment proves its effectiveness,the inspecting accuracy can reach 95.4%.And every inspecting image′s processing time is 100 ms on average.So the inspecting algorithm has the advantage of applicability,generality and convenience.That is very fit for practical application.