误码率(BER)是非对称限幅光正交频分复用(ACO-OFDM)的一项重要性能指标，子载波个数是影响这一性能指标的重要因素。通过理论推导及仿真证明的方法，分析了子载波个数对光域单边带ACO-OFDM信号在单模光纤中传输时系统误码率的影响。结果表明，在总传输速率一定时，改变子载波个数从128个到16384个，所需要的总带宽改变不超过0.775%。并在此基础上，通过实验证明了不同的传输速率下ACO-OFDM系统均存在使系统误码率最低的最优子载波个数，实验结果表明该最优子载波个数随传输速率的增加而增加。

Bit error rate (BER) is a key indicator of asymmetrically clipped optical orthogonal frequency division multiplexing (ACO-OFDM). The number of subcarriers is an important factor of the indicator. By theoretical deduction and simulation, the impact of subcarriers′ number on the BER of ACO-OFDM transmitted in standard single-mode fiber (SSMF) with optical single-sideband (OSSB) modulation is analyzed. Theoretical analysis shows that, when the total transmission rate is constant, changing the number of subcarriers from 128 to 16384, the total bandwidth required changes no more than 0.775%. And based on this, further theoretical analysis and simulation illustrate that, with different transmission rates of ACO-OFDM system, there always exists the optimal number of subcarriers resulting the lowest BER, and the optimal number increases with higher transmission rate.