This invention discloses a 3D printing apparatus and method utilizing friction stir welding (FSW). The apparatus includes a material feeding mechanism, a control mechanism, a friction stir welding (FSW) mechanism, and a friction stir welding (FSW) rotation drive mechanism. The control mechanism controls the material feeding mechanism, the FSW mechanism and the FSW rotation drive mechanism. In addition to the control mechanism, the FSW mechanism also connects to the FSW rotation drive mechanism. The method comprises the steps of: 1, start the control mechanism; step 2, the control mechanism controls the material feeding mechanism to feed filling material; step 3, print 3D product with FSW mechanism. The invention achieves additive manufacturing and 3D printing with a new friction stir welding technology. The invented method has many advantages such as can handle a wide range of raw materials, has high printing speed, has high efficiency, has low energy consumption, requires low cost, is broadly applicable in different situations, is environmentally friendly, and is easy to automate. The products manufactured following this invention is formed through semi-solid forming technology. They will have good mechanical properties and low price.