The magnetic properties of pseudobinary Sm2(FeNiCoM)17 alloys in which M are nonmagnetic elements have been studied. The sample consists of disordered hexagonal 2:17 phase (TbCu7-structure) coexisting with FeNi. Anomalous magnetic properties along the c-axis (easy magnetization direction) have been observed. Below the room temperature, the magnetization and reverse magnetization curves exhibit obvious jumps. The magnetic fields corresponding to the jumps Hr increase with the temperature decreasing. The hysteresis loops show wasp-waisted character. The curve of magnetization vs. temperature has a maximum, the corresponding transition temperature Tt decreases with the magnetic field increasing. During cooling, the thermal magnetic hysteresis phenomena have been found at some values of magnetic field. On the basal plane (hard magnetization direction) and at higher Co concentrations (>18at%), the alloys show normal ferromagnetic behaviors. Most of the phenomena observed can be explained in terms of spin reorientation phase transition leading to non-collinear spin arrangements. The reversal of spin direction must cross over an evergy barrier, the height of which is U = 9.2×10-15 erg. The calculated values of magnetization are in good agreement with the observed ones.