The invention relates to a camera internal parameter calibration method based on a regular triangle template. The regular triangle flat template adopted in the method is a big regular triangle flat template formed by three small regular triangle plates in a splicing mode through abutting joint of angles, the small regular triangle plates are same in size and color, and the side length of the small regular triangle plates can be in any size. The camera internal parameter calibration method includes the following steps that (1), a camera at least shoots 3 template images in different positions; (2) sub-pixel-level image coordinates of six angular points of each template image are extracted; (3) if the size of the template is unknown, by the utilization of the perspective geometry theory and characteristics of the regular triangle flat template, image coordinates of a vanishing point and a circular ring point are calculated, and camera internal parameters are calibrated; (4) if the size of the template and world coordinates of feature points are known, the camera internal parameters can be calibrated through kinds of methods. The regular triangle flat template adopted in the method is suitable for industrial sites, the use method is simple, and an algorithm can ensure enough calibration precision.