The invention discloses a method for making achromatic alteration silver diffraction pattern, comprising the following steps of: (1) preparing a binary optical element whose far-field diffraction optical field is a slot; (2) building a 4F optical system, placing the binary optical element on its conversion plane as a beam splitting element to split incident light into two strip optical fields, which are imaged by lens set to form a speckle interference image unit on the surface of a recording material; (3) changing relative position between the optical system and the recording material to record a corresponding strip speckle interference image unit so as to obtain the achromatic alteration silver diffraction pattern. Besides, the invention provides a device for implementing the method.