The invention relates to digital disks of mechanical digital locks, in particular to an adjustable positioning disk of a digital disk of a mechanical digital lock. The adjustable positioning disk comprises an annular inner disk with a circle center hole and an outer disk; the outer disk and the inner disk are coaxially connected and positioned by a positioning piece; the excircle of the outer disk is provided with a lock card slot; the circle center hole of the inner disk is provided with a positioning guide sliding chute; and inner wall surfaces on two sides of the positioning guide sliding chute are parallel with each other along the radius direction. The adjustable positioning disk has simple structure, can freely adjust the inclined angle between the lock card slot and the positioningguide sliding chute and is convenient to install and debug. When the adjustable positioning disk is applied to a digital disk combination, inclined angles between the center line of the lock card slot of each positioning disk of the digital disk and the center line of the positioning guide sliding chute on the 360-degree circumference are different or not completely same, thereby not only realizing automatic code variation of the digital lock, but also forming a password mode of a curved lock card slot. The invention is particularly suitable to be matched with metal digital locks of various safes, vault doors and burglar-proof vault door.