Embodiments of this application disclose a data processing method, an optical transmission device, and a digital processing chip, for improving service transmission performance. In the data processing method, an optical transmission device compresses a to-be-transmitted data stream to obtain a compressed data stream. The optical transmission device then obtains a size of a first payload area corresponding to the compressed data stream and maps the compressed data stream to a data frame, where the data frame includes an overhead area and a payload area. The payload area includes the first payload area and a second payload area. The second payload area carries the compressed data stream, and the first payload area carries a forward error correction (FEC) code. The data frame is then transmitted by the optical transmission device.