Abstract: Disclosed are a manufacturing method for a support substrate (14), and an LED display device. The support substrate (14) is made of a carbon fiber material. The manufacturing method for the support substrate (14) comprises the steps of: S1: preparing a carbon fiber prepreg fabric; S2: preparing a support substrate (14) sheet; S3: pre-forming; and S4: molding. The LED display device comprises at least one cellular LED display screen (1), and the cellular LED display screen (1) comprises a support substrate (14) manufactured using the abovementioned method. The cellular LED display screen (1) comprises an LED display module, the support substrate (14), a control plate and a back cover (16). The LED display module comprises a face guard (11), a lamp plate (12) and a backing plate (13).