The invention discloses an image edge grading-detection method based on visual pathway orientation sensitivity. A first neural network sensitive to multiple specific directions is established under the action of neuron synaptic connection on receptive field optimal orientation centripetal distribution, an image pixel is taken as network input, a pulse firing sequence of neuron in a certain time window is recorded, and a discharge frequency is calculated to serve as network output; network output in multiple directions is integrated and mapped to a gray scale, and an edge sensitive image is formed; as for the edge sensitive image, the inner lateral inhibition range and the inhibition quantity of a receptive field are determined, a second neural network is formed, and the laterally inhibited image is output; finally, an edge detection result is acquired after threshold processing. According to the method, important vision mechanisms such as directional receptive field, lateral inhibition and the like are considered, the grading processing effect of different levels of structures on a visual pathway during profile sensing is simulated, and the edge detection performance of a long-scale contrast image is improved.