Stimulated-Raman Scattering in the fiber and its continual stokes spectrum were studied. The frequency doubled output of a Q-switched Nd + 3∶YAGlaser centered at 532 nm was used as input pump to excite multi-mode fiber with length of 15m and 120m ,respectively. And we screened 2 orders and 5 orders SRS spectrum lines. Their origin was discussed and their frequency-shifts were measured.We reviewed their character ,and analysed the reason that anti-stokes lines are difficult to arise and the relation of the SRS threshold in the fiber with the length of the fiber. The reason of the continual high-order stokes spectrum was also explained. The theoretical simulation and the experiment agree well.