The non-linear interactions of electromagnetic and spin waves are investigated in the films of yttrium iron garnet (YIG).The aim of the paper is the experimental investigation of non-linear effects at application of the electromagnetic pump field on the YIG film (at propagation of magnetostatical waves in it) and also the construction of theoretical models adequately describing the studied experimental phenomena. During investigation the methods of magnetostatics equations and microwave equipment have been used. The analytical expression has been obtained for parametric excitation threshold of spin waves in case when both the pump and parametrically excited SW belong to the magnetostatic part of spectrum. It has been shown that the parametric excitation threshold depends upon the dimensions of pump localization field that has been connected with energy removal from localization field by spin waves. The amplification of surface magnetostatic waves by a longitudinal pumping has been investigated, and the SMW amplification in continuous regime has been obtained before parametrical excitation of the exchange spin waves. Area of application: SHF spin wave electronicsAvailable from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio