A preparation method for fluidizing and shaping low-cost titanium powder for 3D printing. The specific preparation method comprises: using low-cost irregularly-shaped titanium powder having undergone hydrogenation-dehydrogenation as a powder raw material; placing the titanium powder in a fluidization bed reactor, and introducing Ar or H2 at a gas flow rate of 0.5 to 1.5 L/min; heating the reactor to 300°C to 700°C; performing fluidization for 5 to 90 min, and fluidizing and shaping the titanium powder; allowing, in the presence of flowing highly-pure argon and under the condition of high-temperature heating, sharp edges and corners of the irregularly-shaped titanium powder to be ground by means of collision and friction between powder particles, such that the fluidity of the titanium powder is effectively improved, and an impurity content thereof is effectively controlled. The method employs a simple device and process; has high efficiency, a controllable impurity content, and low preparation costs; and a low-cost titanium powder raw material prepared thereby meets the requirements of powder metallurgy processes such as 3D printing and injection molding.