The SiL2.3 emission spectra of amorphous W/Si multilayers were measured. For the as-deposited samples the SiL2,3 emission spectra have been found to be very close to that of amorphous Si. The formation of WSi2 phase during annealing of W/Si multilayers at a temperature ≥50 °C was detected. From the SiL2,3 emission spectra of as-deposited and annealed samples, the amount of W/Si2 phase was estimated. It is shown that this technique can be used for quantitative estimation of the ratio of amorphous Si and WSi2 phases in W/Si multilayers.