A flat LED channel capable of improving flatness of light emitting surface and manufacturing method thereof are provided to minimize a defect according to an epoxy leak by injecting an epoxy after sealing an outside bottom surface of a frame contacting with a resin film. A manufacturing method of a flat LED channel capable of improving flatness of light emitting surface comprises the following steps: a step for manufacturing a frame having a penetrated part with a specific motif by cutting and bending a silted steel material using a bending machine(S10); a step for arranging the frame on a horizontal support member in order to inverse the specific motif when looking at an upper part(S20); a step for sealing a part contacted in the horizontal support member using an adhere or a sealant(S30); a step for hardening a channel formed by the frame and the horizontal support member after 1st injecting an epoxy(S40); a step for loading a LED module on the 1st injected epoxy(S50); a step for fixing the LED module in the channel by 2nd injecting and hardening an epoxy(S60); and a step for completing a flat LED channel by separating the horizontal support member(S70).
