An electronic state sensitive semiempirical collision-radiative model of hydrogen plasma of ECR-discharge is used to analyze the applicability of emission of triplet states of molecular hydrogen for plasma diagnostics. It is shown that secondary processes make the greatest contribution to the kinetics of population-depopulation of triplet states ${a}^{3}{{\rm{\Sigma }}}_{g}^{+},{c}^{3}{{\rm{\Pi }}}_{u},{d}^{3}{{\rm{\Pi }}}_{u},{e}^{3}{{\rm{\Sigma }}}_{u}^{+},{g}^{3}{{\rm{\Sigma }}}_{g}^{+},{h}^{3}{{\rm{\Sigma }}}_{g}^{+}$, i 3Πg and r 3Πg. The secondary processes give the smallest contribution to the excitation and deactivation of triplet states ${f}^{3}{{\rm{\Sigma }}}_{u}^{+}\,{\unicode{x00438;}}\,{k}^{3}{{\rm{\Pi }}}_{u}$. Thus a simplified coronal model (electron impact excitation followed by radiative decay) can be used to process the intensities of the dipole allowed ${f}^{3}{{\rm{\Sigma }}}_{u}^{+}\,\to \,{a}^{3}{{\rm{\Sigma }}}_{g}^{+},{g}^{3}{{\rm{\Sigma }}}_{g}^{+}$ and ${k}^{3}{{\rm{\Pi }}}_{u}\,\to \,{a}^{3}{{\rm{\Sigma }}}_{g}^{+}$ transitions. The complicated collision-radiative model should be used for other transitions.