A method for automatically measuring microhole includes using CCD camera head and microscope to amplify the image of microhole, inputting it to computer, filtering by area method, finding out the microhole relative to maximal number of pixeles, storing the coordinates of the boundary points of said microhole in a chain table, calculating the coordinate of the central point of said microhole, searching the maximal diameter, choosing the maximum and minimum, and obtaining the average diameter and roundness error. Its equipment is composed of microscope table, light source, object carrier, microhole and carrier plate, object lens, CCD camera head, computer and display. Its advantages are high speed and precision, and high anti-interference power.