In this paper, the multiple access performance of the HFC up channel which is based on SCDMA is analysed. After more research, Walsh code is chosen as the spreading sequence, and QPSK is chosen as the modulation format of up channel. 分析了SCDMA的多址接入性能,在此基础上,通过进一步研究,选择Walsh码作为扩频序列,QPSK作为上行调制方式。