The invention relates to the optical communication technology, in particular to a method for extracting local oscillating light in a Super-channel CO-OFDM system. The local oscillating light is extracted in the Super-channel CO-OFDM system with the method that optical injection locking is combined with an optical phase-locked loop, the complexity of an optical receiver to be used for compensating for frequency offset and phases can be effectively lowered, and the power consumption, the cost and the like of the receiver can be further reduced. According to the method, as photon carriers extracted after processing such as optical injection locking and phase locking is carried out serve as the local oscillating light, the local oscillating light can be kept the same as the signal photon carriers in frequency and phase, the complexity of a digital signal processing algorithm in the coherent optical receiver can be greatly lowered, the power consumption of the digital signal processing algorithm in the coherent optical receiver can be greatly reduced, and the performance advantages, including the receiver sensitivity, the spectral efficiency and the robustness to polarization dispersion, of the CO-OFDM can be better developed. In addition, by means of the method, the CO-OFDM system can have the high operation efficiency, and reduction, caused by the frequency deviation between a local laser apparatus and a transmitting-end laser apparatus, of the coherent receiving efficiency can be effectively reduced.