Spread spectrum signals are now widely used for secure communications, as well as for multiple access interference (MAI). They have many interesting properties, including low probability of interception. Indeed, DS/SS transmitters use a periodical pseudo-random sequence to modulate the baseband signal before transmission. A receiver which does not know the sequence can not demodulate the signal. Blind estimation of m-sequence is only discussed openly in the situation without multi-path interference and MAI so far. In this paper, we use the independent component analysis (ICA) to separate the data bits transmitted by different users in multi-path, and then identify m-sequence according to the triple correlation function (TCF) of m-sequence. The performance of this blind estimation is analyzed under Gaussian noise. Illustrative simulation examples are provided at last.