The method proposed allows us to determine stress-strain states inside composite materials by using implantable thin-film resistive-strain tensors SmS. The thickness of resistive-strain tensors is 1 mm, the length is ranged from 5 mm to 10 cm. When using resistive-strain tensors of such dimensions, we can avoid the main difficulties arising in the strain measurement method on relatively small bases. The coefficient of strain sensibility may be varied in the range K=10–130; as a result, we can obtain an output signal of large amplitude. When processing output data, we use no methods of the theory of probability. The results obtained by the method proposed are compared with the experimental data obtained by using the Instron loading machine.