SmFe1_xMnxO3 (x = 0.0, 0.1, 0.3) polycrystalline powder samples were prepared by sol-gel method, and the obtained samples were all orthorhombic structures with Pbnm space group. M & ouml;ssbauer spectroscopy at room temperature confirmed the +3 oxidation state of iron. All samples were fitted by sextet spectra, indicating that the samples are magnetically ordered at room temperature. The zero-field-cooled and field-cooled curves of SmFe0.9Mn0.1O3 sample show a reverse crossover trend at 5 K, and the magnetization is significantly enhanced after reaching the spin-switching transition temperatur...