The present application provides a method and a device for expanding a lens image into a panoramic image, the method includes: step A, preparing an original mesh model, calculating new mapping coordinate values, performing coordinate value transformation for the original mapping coordinate values of the original mesh model and the calculated new mapping coordinate values, and generating a new mesh model and storing the new mesh model; and step B, preparing a lens image to be expanded, assigning the lens image to be expanded to the new mesh model in step A, and rendering the new mesh model by a GPU to obtain a panoramic image and store the panoramic image.