A method for determining the dielectric permittivity of a dielectric object against the background of a reflector, the method comprising: irradiating the dielectric object with coherent microwave radiation at N frequencies, detecting the signal reflected from the dielectric object and the reflector, whereby the method further comprises: coherent processing of the detected signal and receiving three dimensional microwave image of the dielectric object and the reflector, wherein the microwave image corresponds to only one three dimensional surface formed with points corresponding to the maximal values of intensity of the reconstructed configuration of the scatterers of the dielectric object and the reflector; additionally obtaining a video image of a region, where the dielectric object and the reflector are located by using two or more video cameras, synchronized with the microwave radiation source; converting the obtained video image into digital form a constructing a tree-dimensional video image of said region; converting the three dimensional video image and the microwave image into a general system of coordinates; from the microwave image in the general system of coordinates determining the distance Z 1 between the microwave radiation source and a section of the microwave image of the reflector that is free of the dielectric object, and the distance Z 2 between the microwave radiation source and the section of the microwave image of the reflector in the region of the dielectric object; on the basis of the video image determining in the general system of coordinates the distance Z 3 between the microwave radiation source and the video image of the dielectric object; whereby the dielectric permittivity ε of the dielectric object is determined from the relationship: ε = z 2 - z 3 z 1 - z 3 2. irradiating the dielectric object with coherent microwave radiation at N frequencies, detecting the signal reflected from the dielectric object and the reflector, whereby the method further comprises: coherent processing of the detected signal and receiving three dimensional microwave image of the dielectric object and the reflector, wherein the microwave image corresponds to only one three dimensional surface formed with points corresponding to the maximal values of intensity of the reconstructed configuration of the scatterers of the dielectric object and the reflector; additionally obtaining a video image of a region, where the dielectric object and the reflector are located by using two or more video cameras, synchronized with the microwave radiation source; converting the obtained video image into digital form a constructing a tree-dimensional video image of said region; converting the three dimensional video image and the microwave image into a general system of coordinates; from the microwave image in the general system of coordinates determining the distance Z 1 between the microwave radiation source and a section of the microwave image of the reflector that is free of the dielectric object, and the distance Z 2 between the microwave radiation source and the section of the microwave image of the reflector in the region of the dielectric object; on the basis of the video image determining in the general system of coordinates the distance Z 3 between the microwave radiation source and the video image of the dielectric object; whereby the dielectric permittivity ε of the dielectric object is determined from the relationship: ε = z 2 - z 3 z 1 - z 3 2. coherent processing of the detected signal and receiving three dimensional microwave image of the dielectric object and the reflector, wherein the microwave image corresponds to only one three dimensional surface formed with points corresponding to the maximal values of intensity of the reconstructed configuration of the scatterers of the dielectric object and the reflector; additionally obtaining a video image of a region, where the dielectric object and the reflector are located by using two or more video cameras, synchronized with the microwave radiation source; converting the obtained video image into digital form a constructing a tree-dimensional video image of said region; converting the three dimensional video image and the microwave image into a general system of coordinates; from the microwave image in the general system of coordinates determining the distance Z 1 between the microwave radiation source and a section of the microwave image of the reflector that is free of the dielectric object, and the distance Z 2 between the microwave radiation source and the section of the microwave image of the reflector in the region of the dielectric object; on the basis of the video image determining in the general system of coordinates the distance Z 3 between the microwave radiation source and the video image of the dielectric object; whereby the dielectric permittivity ε of the dielectric object is determined from the relationship: ε = z 2 - z 3 z 1 - z 3 2.