The invention belongs to the technical field of filters, and provides a simulation method and simulation device for a C-band waveguide filter, a terminal and a readable storage medium, and the methodcomprises the steps: building an initial waffle model through obtaining initial waffle parameters inputted by a user; obtaining initial geometric parameters input by a user, establishing a cuboid model, and setting matching nodes on the cuboid model; wherein the cuboid model wraps the initial waffle model; setting a port at each of two ends of the cuboid model, and establishing an initial waveguide filter model; judging whether the S parameter of the initial waveguide filter model is within a preset range or not; and if yes, outputting the current initial waveguide filter model, and generatinga target size parameter of the waveguide filter, and if not, adjusting the initial waffle parameter and the initial geometric parameter until the S parameter of the initial waveguide filter is withina preset range. Therefore, under the condition of the same model length, the required waveguide filter can be rapidly simulated in a short period, the production time is saved, and the production cost is reduced.