A photography auxiliary device for a mobile communication unit, including: a bottom plate (1), a lens hole (11) arranged on the bottom plate (1), a shaft (7), walls surrounding the base plate (1), a gear (6) rotatably connected to the shaft (7), and a first rack (4) and a second rack (5) at opposite ends of the gear (6); the wall includes a first side wall (2) and a second side wall (3), the first side wall (2) is provided with a groove (21), the second side wall (3) is provided with a through hole (31); an end portion of the first rack (4) is provided with a shutter button (41) located in the through hole (31); an end portion of the second rack (5) is provided with an elbow (51) located in the groove (21); the second rack (5) is arranged in parallel with the first rack (4). When the shutter button (41) is pressed, the elbow (51) moves upward together with the second rack (5) and presses the volume button for driving the photography.