  As part of the search for new physics beyond the Standard Model, we chose the
determination of the Higgs boson decay width as one of the least experimentally
determined values. The decay widths into the four fermions of the lightest and
heaviest CP-even Higgs bosons of the THDM model were calculated, taking into
account QCD and electroweak corrections in the NLO approximation. To achieve
this goal, the program Monte Carlo Prophecy 4f with special scenarios of
parameters, 7B1 and 5B1 were used. It was found that the decay width of the
heavier CP-even Higgs boson, H differs from H$_{SM}$ by 1227.93 times and
changes to a negative value when deviating from the standard scenarios. Scale
factors k$^2_{Z}$ and k$^2_{W}$ showed the predominance of the associated with
Z boson production cross section of CP-even Higgs boson over the associated
with W production cross section.
