In this work, the influences of several parameters (molecular density of medium, transition linewidth, photon density of pump laser and nonlinear interaction length) on high pressure H2 stimulated Raman scattering (SRS) threshold and energy transfer efficiency are investigated. The experiments were carried out on a Q(1) line vibration transition (4155 cm-1) SRS. Results of effect of H2 pressure (0 to 24 atm) on the threshold are coincident with the analysis of the combined effect of Dicke-Doppler and collision broadening. The influences of stimulated Raman process (SRP) and four-wave parametric processes (FWPP) on energy transfer efficiency, as well as the role of pressure-dispersion effect on higher order anti-Stokes are also discussed.