In this research, first, nanoparticles of SrFe11.98Mg0.1Sn0.1O19 hexaferrite was synthesized via sol-gel autocombustion process and then the nanocomposites of hexagonal ferrites/perovskite with the amounts of SrFe11.98Mg0.1Sn0.1O19 /BaTiO3 (50/50, 40/60, 70/30 w/w) was prepared by ball-milling method. FTIR spectra were shown that the bands at about 400 and 500 cm-1 proved the formation of hexagonal ferrites. XRD analysis was confirmed the formation of hexaferrite and perovskite phase of BaTiO3. FESEM pictures was represented the formation of hexagonal nanoparticles and sphere shape of BaTiO3. VSM hysteresis loop was revealed that SrFe11.98Mg0.1Sn0.1O19 belonged to the soft magnetic materials due to the 604.45Oe coercivity. By formation of nanocomposites the coercivity was increased up to 1500 Oe. VNA analysis was VNA analysis revealed that the maximum absorption of -16.4db at 11.5 GHz frequency for SrFe11.98Mg0.1Sn0.1O19 /BaTiO3 (60/40) nanocomposite. Microwave absorption properties of samples was investigated by (vector network analyzer) VNA. The maximum value of reflection loss was --16.4db at 11.5 GHz frequency for SrFe11.98Mg0.1Sn0.1O19 /BaTiO3 (60/40) nanocomposite.