The present application provides a method, apparatus, device and medium for optimizing thresholds based on K-edge imaging. The method comprises: pre-scanning, by using a photon counting detector, an object to be detected according to a preset threshold group, to obtain first detection data； determining, according to the first detection data, line integral values of decomposition coefficients of individual basis functions in a basis function combination of each ray, wherein each ray has a fixed basis function combination； selecting, according to the line integral values of the decomposition coefficients of individual basis functions in the basis function combination of the each ray, rays of which a line integral value of a contrast agent material basis function in the fixed basis function combination is greater than a preset line integration threshold； inputting detection data corresponding to each of the selected rays to a pre-trained neural network model, to obtain a local optimal threshold group of each of the selected rays； and determining, based on local optimal threshold groups, a global optimal threshold group for the K-edge imaging of the photon counting detector.
