A assembled support mechanism for an LED display screen, comprises: a bottom support, being in an assembled frame structure, provided with devices configured for longitudinal and transverse splicing at a periphery thereof, and the devices configured for longitudinal and transverse splicing comprising a longitudinal engagement device and a transverse engagement device; and middle portions of a front side and a rear side of the bottom support being respectively provided with screen connecting portions configured for connecting to an LED display screen in a vertical direction. A plurality of rotational stands, in detachable connection with the bottom support, and a respective rotational stand after being spliced and assembled being rotatable around the bottom support with a rotational angle range of 0° to 180°.