An LED module mounting mechanism, comprising: a fixing frame, the fixing frame comprising a horizontal frame and a vertical frame, an extending direction of the horizontal frame being defined as X-axis direction and the extending direction of the vertical frame being defined as Y-axis direction; at least three gap adjusting mechanisms respectively mounted on the horizontal frame and the vertical frame, a gap adjusting mechanism mounted on the horizontal frame being defined as a Y-axis adjustment mechanism, and a gap adjusting mechanism mounted on the vertical frame being defined an X-axis gap adjusting mechanism; and four movable blocks movably connected with the fixing frame, the four movable blocks being respectively disposed on two sides of the horizontal frame and two sides of the vertical frame, and showing a grid pattern, the movable blocks disposed on the two sides of the horizontal frame being movable along the X-axis direction and the moving blocks disposed on the two sides of the vertical frame being movable along the Y-axis direction; LED modules being arranged on the movable blocks, respectively, and two ends of each gap adjusting mechanism being connected with two of the movable blocks, respectively; a gap in the X-axis direction or the Y-axis direction between the LED modules arranged on the movable blocks being respectively adjusted by regulating the X-axis gap adjusting mechanism or the Y-axis gap adjusting mechanism to move the movable blocks on the two ends toward or away from each other; characterized in that the Y-axis gap adjusting mechanism is mounted on the horizontal frame in a manner capable of moving as a whole along the X-axis direction, and the X-axis gap adjusting mechanism is mounted on the vertical frame in a manner capable of moving as a whole along the Y-axis direction; the horizontal frame is provided with a first through hole with a cross section elongated in the X-axis direction, the vertical frame is provided with a second through hole with a cross section elongated in the Y-axis direction, the X-axis gap adjusting mechanism is movably disposed within the second through hole and two ends of the X-axis gap adjusting mechanism extend out of the second through hole and are respectively connected to left and right movable blocks, such that the two movable blocks are capable of being driven to move toward or away from each other along the X-axis direction; and the Y-axis gap adjusting mechanism is movably disposed within the first through hole and two ends of the Y-axis gap adjusting mechanism extend out of the first through hole and are respectively connected to upper and lower movable blocks, such that the two movable blocks are capable of being driven to move toward or away from each other along the Y-axis direction. a fixing frame, the fixing frame comprising a horizontal frame and a vertical frame, an extending direction of the horizontal frame being defined as X-axis direction and the extending direction of the vertical frame being defined as Y-axis direction; at least three gap adjusting mechanisms respectively mounted on the horizontal frame and the vertical frame, a gap adjusting mechanism mounted on the horizontal frame being defined as a Y-axis adjustment mechanism, and a gap adjusting mechanism mounted on the vertical frame being defined an X-axis gap adjusting mechanism; and four movable blocks movably connected with the fixing frame, the four movable blocks being respectively disposed on two sides of the horizontal frame and two sides of the vertical frame, and showing a grid pattern, the movable blocks disposed on the two sides of the horizontal frame being movable along the X-axis direction and the moving blocks disposed on the two sides of the vertical frame being movable along the Y-axis direction; LED modules being arranged on the movable blocks, respectively, and two ends of each gap adjusting mechanism being connected with two of the movable blocks, respectively; a gap in the X-axis direction or the Y-axis direction between the LED modules arranged on the movable blocks being respectively adjusted by regulating the X-axis gap adjusting mechanism or the Y-axis gap adjusting mechanism to move the movable blocks on the two ends toward or away from each other; characterized in that the Y-axis gap adjusting mechanism is mounted on the horizontal frame in a manner capable of moving as a whole along the X-axis direction, and the X-axis gap adjusting mechanism is mounted on the vertical frame in a manner capable of moving as a whole along the Y-axis direction; the horizontal frame is provided with a first through hole with a cross section elongated in the X-axis direction, the vertical frame is provided with a second through hole with a cross section elongated in the Y-axis direction, the X-axis gap adjusting mechanism is movably disposed within the second through hole and two ends of the X-axis gap adjusting mechanism extend out of the second through hole and are respectively connected to left and right movable blocks, such that the two movable blocks are capable of being driven to move toward or away from each other along the X-axis direction; and the Y-axis gap adjusting mechanism is movably disposed within the first through hole and two ends of the Y-axis gap adjusting mechanism extend out of the first through hole and are respectively connected to upper and lower movable blocks, such that the two movable blocks are capable of being driven to move toward or away from each other along the Y-axis direction.