In my talk I want to tell about recently achieved(2011)by I.Kossovsky and myself complete local classification of 4-dimensional CR-manifolds,which represents the next step to the famous E.Cartans classification of 3-dimensional CR-manifolds(1932).Also I will observe modern condition of analytical approach to CR-manifolds study-the approach of a model surface,on which the achieved classification is based and which was initiated by the pioneer work of H.Poincaré(1907)and was developed in papers of Chern and Moser(1974)and,also,works of myself.