The invention relates to an automatic star finder control apparatus for a portable astronomical telescope and its control method. The apparatus comprises power input interface, main controller, equatorial instrument driving controller. The main controller includes central processing unit (CPU), random accessing memory (RAM), flash memory (FLASH), press-key, graphical dot matrix liquid crystal display, buzzer, white light-emitting diode back lamp, white light-emitting lighting lamp, RS232 serial interface, internal serial bus; the equatorial instrument includes single chip micro processor, dual-direction reversible PWM driving circuit, direct current motor, photoelectricity code disc and photoelectricity code disc detecting circuit, current foldback circuit. The invention controls motion of the equatorial instrument driving controller via calculating coordinate of object celestial body in the equatorial instrument with the micro processor of the main controller, realizing pointing and tracking the object celestial body with telescope.