An experimental observation of the competition between quantum interference and stimulated electronic Raman scattering (SERS) via equal-frequency hybrid excitation and collision-aided radiative excitation in a Na2-Na system is reported for the first time.It is found that the SERS for 3P1/2,3/2-4P are suppressed and the optically pumped stimulated emission (OPSE) for 5S-4P are enhanced dramatically at a particular excitation wavelength where constructive quantum interference between two transitions 3P1/2-5S and 3P3/2-5S in atomic sodium takes place.A theoretical analysis based on the dressed-atom approach is carried out to explain the experimental results.