A Time Division Multiplexing -based Forward Error Correction coding method for mixed services, comprising: receiving at least one path of Optical Data Unit TDM service signal, comprising a multiplex of the mixed services; maintaining an input multiplexing relationship of the mixed services in the ODU TDM service signal, and performing four-byte parallel coding processing on each code block of each of the still multiplexed services to obtain an Optical Transfer Unit TDM service signal, wherein intermediate coding results for each service are separately stored in remainder registers corresponding to each service; and outputting the OTU TDM service signal, wherein the ODU TDM service signal is a 512-bit TDM service signal, wherein the step of performing four-byte parallel coding processing on each code block of the ODU TDM service signal to obtain an OTU TDM service signal comprises: duplicating the ODU TDM service signal into two paths of data, wherein a first path of data is transmitted into a First In First Out (FIFO) circuit, and a second path of data is taken as operational data to calculate coded information; performing delaying processing on the first path of data to obtain a delayed ODU TDM service signal by virtue of the FIFO circuit; performing interleaving processing on the second path of data; transmitting the interleaved data into a coder, and performing four-byte parallel coding processing on the interleaved data to obtain coded check information; performing de-interleaving processing on the coded check information; and forming the OTU TDM service signal by combining the de-interleaved check information and the delayed ODU TDM service signal, wherein the step of transmitting the interleaved data into a coder and performing four-byte parallel coding processing on the interleaved data to obtain coded check information comprises: transmitting the interleaved data into 16 sub-coders respectively; performing four-byte data parallel coding in each sub-coder; and wherein for each service, a FEC valid signal indicates that the check information for the service is to be output, and when check information is completely output, the FEC valid signal gets invalid. receiving at least one path of Optical Data Unit TDM service signal, comprising a multiplex of the mixed services; maintaining an input multiplexing relationship of the mixed services in the ODU TDM service signal, and performing four-byte parallel coding processing on each code block of each of the still multiplexed services to obtain an Optical Transfer Unit TDM service signal, wherein intermediate coding results for each service are separately stored in remainder registers corresponding to each service; and outputting the OTU TDM service signal, wherein the ODU TDM service signal is a 512-bit TDM service signal, wherein the step of performing four-byte parallel coding processing on each code block of the ODU TDM service signal to obtain an OTU TDM service signal comprises: duplicating the ODU TDM service signal into two paths of data, wherein a first path of data is transmitted into a First In First Out (FIFO) circuit, and a second path of data is taken as operational data to calculate coded information; performing delaying processing on the first path of data to obtain a delayed ODU TDM service signal by virtue of the FIFO circuit; performing interleaving processing on the second path of data; transmitting the interleaved data into a coder, and performing four-byte parallel coding processing on the interleaved data to obtain coded check information; performing de-interleaving processing on the coded check information; and forming the OTU TDM service signal by combining the de-interleaved check information and the delayed ODU TDM service signal, duplicating the ODU TDM service signal into two paths of data, wherein a first path of data is transmitted into a First In First Out (FIFO) circuit, and a second path of data is taken as operational data to calculate coded information; performing delaying processing on the first path of data to obtain a delayed ODU TDM service signal by virtue of the FIFO circuit; performing interleaving processing on the second path of data; transmitting the interleaved data into a coder, and performing four-byte parallel coding processing on the interleaved data to obtain coded check information; performing de-interleaving processing on the coded check information; and forming the OTU TDM service signal by combining the de-interleaved check information and the delayed ODU TDM service signal, wherein the step of transmitting the interleaved data into a coder and performing four-byte parallel coding processing on the interleaved data to obtain coded check information comprises: transmitting the interleaved data into 16 sub-coders respectively; performing four-byte data parallel coding in each sub-coder; and wherein for each service, a FEC valid signal indicates that the check information for the service is to be output, and when check information is completely output, the FEC valid signal gets invalid. transmitting the interleaved data into 16 sub-coders respectively; performing four-byte data parallel coding in each sub-coder; and wherein for each service, a FEC valid signal indicates that the check information for the service is to be output, and when check information is completely output, the FEC valid signal gets invalid.