This study systematically collected and organized seismic intensity isolines and relevant damage investigation data for 44 seismic events in the Loess Plateau region of China. We used a constrained model of seismic intensity ellipses and applied a two-step regression with double weighting to establish seismic intensity attenuation relationships for the western and eastern regions of the Loess Plateau. We ensured that the long and short axes of the intensity ellipses at epicentral and far-field distances had approximately equal intensity values by imposing additional fitting constraints. A comparative analysis of seismic intensity attenuation relationships in other regions revealed distinct regional characteristics in the Loess Plateau area. In most cases, at equivalent distances, the intensity values in the western region of the Loess Plateau are higher than those in the Qinghai—Xizang Plateau, with a maximum difference of 0.8. For short epicentral distances, the intensity values along the long and short axes in the eastern region of the Loess Plateau are lower than those in China's eastern strong earthquake zone. As the distance increases, the intensity values in this region gradually surpass those in the strong earthquake zone of eastern China due to the slow attenuation rate of intensity in the Loess Plateau's eastern region.