Stimulated Raman scattering (SRS) in H2 and H2:He-Ar mixture gases pumped by a pulsed Nd:YAG laser at 355 nm was investigated. Under 0.5 MPa H2, multi-wavelength output was simultaneously measured from the second-order anti-Stokes to the third-order Stokes, with a total conversion efficiency of 88%, while only the first- and the second-order Stokes output were obtained under high pressures, with a maximum energy conversion efficiency for the second-order Stokes as high as 44% (i.e., quantum efficiency of 63%). Due to the competitive suppression by high-order Stokes, the energy conversion efficiency for the first-order Stokes is no more than 43% in pure H2. By adding 2 MPa Ar into 3 MPa H2, the second-order Stokes was greatly suppressed and the first-order Stokes output reached an energy conversion efficiency as high as 71% (i.e., quantum efficiency of 83%). The effect of four-wave mixing (FWM) and cascade SRS on multi-order Stokes generation and the influence of inert gas were discussed.