Understanding spin control mechanisms is an important part of condensed matter physics and the theoretical basis for designing spintronic devices. In this letter, based on four-sublattices molecular field theory, we propose that the underlying NdFe1-xCrxO3 magnetic mechanism is driven by spin reorientation sensitive to temperature. The actual coupling angular momentum, angle between the Nd3+ and Cr3+/Fe3+ moments at the given temperature is realized via the Nd3+ magnetic moment projection onto the Cr3+/Fe3+ plane. As the temperature increases, the angle between the moment of Nd3+ and the moment of Cr3+/Fe3+ decreases monotonically. In this work, the magnetic mechanism of NdFe1-xCrxO3 (x=0.1, 0.9), the close relationship between A/B angle and temperature are presented, which laid a theoretical foundation for the design of new multifunctional magnetic materials.