The invention discloses an electron beam divergence angle measuring device and a preparation method and a measuring method thereof. The device comprises a fluorescent screen and tungsten micro-nano patterns, tungsten hexacarbonyl is deposited on the fluorescent screen through a helium ion microscope to form the tungsten micro-nano patterns, the tungsten micro-nano patterns are a plurality of concentric circles, and the circle centers of the concentric circles are located in the center of the fluorescent screen. A tungsten micro-nano pattern is constructed on a fluorescent screen by utilizing ion-assisted deposition of a helium ion microscope, when the fluorescent screen is moved, the spot shape and the size of an electron beam hit on the fluorescent screen are changed, and an electron beamspot and an electron beam divergence angle are directly measured according to the size and the size of the tungsten micro-nano pattern. The device has the advantages of multiple functions, high measurement precision, simple operation and the like; the preparation method has the advantages of high precision, easiness in control, simple process and the like.