On a basis of field and numerical experiments the evolution of irregular waves with group structure from deep to shallow water are studied. It has been found that on deep water the wave group structure is determined by non-linear properties of waves and looks as automodel process. The non-linear processes are the basic reason of degradation of wave group structure towards to the shore. That is determined by non-linear reorganisation of a wave spectrum in the frequency band of the first harmonics and filling intervals between wave groups of the first harmonics by wave groups of highest harmonics. Wave breaking does not influence directly on wave group structure change. It is revealed three types of dependencies of energy dissipation on frequency during wave breaking: uniform (in outer part of surf zone), square and selective (in inner part of surf zone), which one is determined by asymmetry of waves and bed slope. It is established, that the energy dissipation of breaking waves compensates processes of linear and nonlinear transformations of waves.
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