A service data transmission method, a related device, and a digital processing chip, to reduce a transmission latency of service data. The method in the embodiments includes the following steps: a first device encapsulates a channel frame in a transmission frame, where the channel frame is used to carry service data. Next, the first device sends the transmission frame to a second device. A transmission manner of the channel frame is a non-decapsulation manner between an optical transport network and an access network.