The measurement of the cross section ratio $\sttbb/\sttjj$ is presented using a data sample corresponding to an integrated luminosity of 2.3~$\rm{fb}^{-1}$ collected in pp collisions at \\ $\sqrt{s}$ = 13TeV with the CMS detector at the LHC.
Events with two leptons and at least four reconstructed jets, including at least two identified as b quark jets, in the final state are selected.
The measured ratio is $0.022 \pm 0.003$(stat.)$\pm0.006$(syst.) in the full phase space.
The measured cross section $\sttbb$ is $3.9 \pm 0.6$(stat.)$\pm1.3$(syst.) pb and $\sttjj$ is $176 \pm 5$(stat.)$ \pm 33 $(syst.) pb.