<p>Ni₄Ti₃ precipitates significantly affect the properties of NiTi alloys, including during the laser additive manufacturing ((L-AM) processes, and the formation mechanism of these precipitates in LAM remain unclear.This paper hypothesizes that two factors drive Ni₄Ti₃ precipitation: (1) formation of the Ni-rich regions due to supersaturation of the Ni elements; (2) precipitation of the Ni₄Ti₃ phases adjacent to the Ni-rich regions due to the repetitive deposition processes. Experiments were designed and conducted to verify these two hypotheses. Bulk NiTi parts with and without Ni-rich regions were fabricated by adjusting the raw material compositions to confirm the first hypothesis. Single tracks were deposited and reheated to investigate the influences of the repetitive deposition process on the precipitation of the Ni₄Ti₃ phases. Then, microstructural characterizations and phase analyses were conducted on different regions of the bulk parts and the single tracks to analyze material compositions, identify phase constituents, and observe the morphologies of the Ni₄Ti₃ precipitates. It was found the formation of the Ni-rich regions was the prerequisite and the repetitive reheating of the materials was necessary for the precipitation of the Ni₄Ti₃ precipitates in L-AM of NiTi alloys.</p>