Abstract: A plastic fiber cable coupling structure includes two symmetric coupling pieces coupling with each other. The coupling piece includes a male and a female kit, the male kit has a fixing block and a flange disposed at each side thereof, and two cone-shaped fiber channels disposed therein. Besides, the female kit has a connecting hole disposed at each side thereof, a fastening block disposed at each inner side thereof, and two fiber channels disposed therein, wherein a plurality of detent bodies extend outwardly from the inner side of a first fiber channel, a coupling hole is dug out on the outer side of the first fiber channel, a guiding face is formed on the inner side of a second fiber channel with a plurality of detent bodies extending outwardly, and a coupling end extends outwardly from the outer side of the second fiber channel with a guiding face formed inside the coupling end.