Assuming that the Raman gain profile of silica fiber is a triangular function, we derive analytic solutions of N-channel steady-state forward SRS coupling wave equation with equal (but arbitrary) channel spacing. Considering the SRS cross coupling among N-channels, the analytic solutions are applicable to arbitrary signal light power. The results point out that the sequence mi=pi(z)/pi(0) 〔pi(z) and pi(0) is the power of signal light of i-th channel at transmission length z and 0, respectively. i=1,2,…，N〕 maintains a geometric progression with the common ratio q in the transmission process. The common ratio q varies as a exponential function of the effective transmission length, the sum of input light power and the channel spacing, respectively.