The invention discloses an automatic focusing method for an automatic
microscope. The method comprises the following steps of: a preprocessing step of moving a focusing device on the automatic
microscope onto a slide, acquiring an image of a current position, calculating definition of the image, setting the definition and a position of the current position as initial definition and position,, andsetting a preset step length and an initial direction; a searching step of searching a
peak value with the preset step length and acquiring a rising edge and a falling edge; and a fitting step of fitting the
peak value and the rising edge as well as the falling edge, finding out an optimal focal plane position and moving the focusing device on the automatic
microscope to the position so as to complete the focusing process. By foreground region extraction, measurement of the
peak value and the rising edge as well as the falling edge, parabola fitting and four-point single-
peak fitting, the automatic focusing method for the automatic microscope solves the problems that a conventional automatic focusing method is insufficient in focusing speed and accuracy and particularly is lower in accuracy when focusing is carried out on a view field with an ultralow contrast or an ultra few foreground contents.