Magnetic refrigeration technology, featuring environmental friendliness, energy efficiency and high performance, is recognized as a next-generation refrigeration technology with the potential to replace gas compression refrigeration technology. However, current magnetic refrigeration materials typically exhibit an excessively narrow phase transition temperature range (≤ 10 K), necessitating the stacking of materials with multiple compositions to meet the practical refrigeration temperature span. In this study, the typical La(Fe, Si)₁₃-based magnetic refrigeration material was selected, and an innovative gradient laser powder bed fusion technology was adopted to 3D-print La_0.70Ce_0.30Fe_11.65-xMnxSi_1.35 alloys with horizontal compositional gradients (where the Mn content varies continuously from 0 to 0.64). Systematic characterization of their microstructure, magnetic properties, and magnetocaloric effect indicates that this technology enables controllable gradient distribution of compositions along the powder bed plane and high-throughput preparation, thereby achieving a continuous variation of the Curie temperature of the gradient alloy over a wide temperature range from 134 K to 174 K. With the increase of Mn content, the phase transition of the alloy gradually transforms from a weak first-order phase transition to a second-order phase transition, and the peak shape of the magnetic entropy change curve shifts from "sharp and high" to "broad and flat". The full width at half maximum of the temperature range expands to 83.3 K, allowing the gradient alloy to consistently maintain a high refrigeration capacity (RC ~130 J kg^-1， 3 T). This study breaks through the bottlenecks of traditional material preparation and performance via gradient additive manufacturing, providing a novel technical pathway for the high-throughput preparation and performance optimization of magnetic refrigeration materials.