An asymmetrically clipped optical (ACO) multi-carrier (MC) code division multiple access (CDMA) system is proposed based on CDMA and ACO orthogonal frequency division multiplexing. The theoretical expression of signal-to-noise ratio for the system affected by clipping noises is derived with the orthogonality restoring combining (ORC), maximum ratio combining (MRC) and equal gain combining (EGC) algorithms in the sight and sattering propagation channels. The model for Monte Carlo bit-error-ratio (BER) simulation is established. The reasearch results show that the BER performance can be improved with an increase in the length of spreading codes. As the number of users increases, the MRC algorithm deteriorates due to the muli-user disturbance, however the ORC algorithm maintains the orthogonality among different users and demonstrates the best BER performance. The proposed system outperforms the Flip-MC-CDMA and the unipolar multi-carrier CDMA (U-MC-CDMA) systems.